Method and apparatus for reciprocity based CSI-RS transmission and reception

ABSTRACT

A method for operating a user equipment (UE) comprises receiving configuration information for at least one channel state information reference signal (CSI-RS) resource that comprises P CSIRS  CSI-RS ports; receiving configuration information for channel state information (CSI) feedback that is based on Q precoding dimensions, wherein: there is a mapping between the P CSIRS  CSI-RS ports and the Q precoding dimensions, and P CSIRS ≠Q; measuring the P CSIRS  CSI-RS ports; determining a measurement for the Q precoding dimensions based on the mapping and the measurement for the P CSIRS  CSI-RS ports; determining a CSI feedback based on the measurement for the Q precoding dimensions; and transmitting, over an uplink (UL) channel, the determined CSI feedback.

CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY

The present application claims priority to U.S. Provisional PatentApplication No. 62/956,973, filed on Jan. 3, 2020 and U.S. ProvisionalPatent Application No. 63/112,346, filed on Nov. 11, 2020. The contentof the above-identified patent documents is incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates generally to wireless communicationsystems and more specifically to reciprocity based channel stateinformation reference signal (CSI-RS) transmission and reception.

BACKGROUND

Understanding and correctly estimating the channel between a userequipment (UE) and a base station (BS) (e.g., gNode B (gNB)) isimportant for efficient and effective wireless communication. In orderto correctly estimate the DL channel conditions, the gNB may transmit areference signal, e.g., CSI-RS, to the UE for DL channel measurement,and the UE may report (e.g., feedback) information about channelmeasurement, e.g., CSI, to the gNB. With this DL channel measurement,the gNB is able to select appropriate communication parameters toefficiently and effectively perform wireless data communication with theUE.

SUMMARY

Embodiments of the present disclosure provide methods and apparatuses toenable channel state information (CSI) reporting in a wirelesscommunication system.

In one embodiment, a UE for CSI reporting in a wireless communicationsystem is provided. The UE includes a transceiver configured to receiveconfiguration information for at least one channel state informationreference signal (CSI-RS) resource that comprises P_(CSIRS) CSI-RSports; and receive configuration information for channel stateinformation (CSI) feedback that is based on Q precoding dimensions,wherein: there is a mapping between the P_(CSIRS) CSI-RS ports and the Qprecoding dimensions, and P_(CSIRS)≠Q. The UE further includes aprocessor operably connected to the transceiver. The processor isconfigured to measure the P_(CSIRS) CSI-RS ports; determine ameasurement for the Q precoding dimensions based on the mapping and themeasurement for the P_(CSIRS) CSI-RS ports; and determine a CSI feedbackbased on the measurement for the Q precoding dimensions. The transceiveris further configured to transmit, over an uplink (UL) channel, thedetermined CSI feedback.

In another embodiment, a BS in a wireless communication system isprovided. The BS includes a processor configured to generateconfiguration information for at least one channel state informationreference signal (CSI-RS) resource that comprises P_(CSIRS) CSI-RSports; and generate configuration information for channel stateinformation (CSI) feedback that is based on Q precoding dimensions,wherein: there is a mapping between the P_(CSIRS) CSI-RS ports and the Qprecoding dimensions, and P_(CSIRS)≠Q. The BS further includes atransceiver operably connected to the processor. The transceiver isconfigured to: transmit the configuration information for the at leastone CSI-RS resource; transmit the configuration information for the CSIfeedback; transmit the at least one CSI-RS resource from the P_(CSIRS)CSI-RS ports; and receive, over an uplink (UL) channel, the CSIfeedback; wherein: the CSI feedback is based on the Q precodingdimensions, and the Q precoding dimensions are based on the mapping andthe P_(CSIRS) CSI-RS ports.

In yet another embodiment, a method for operating a UE is provided. Themethod comprises: receiving configuration information for at least onechannel state information reference signal (CSI-RS) resource thatcomprises P_(CSIRS) CSI-RS ports; receiving configuration informationfor channel state information (CSI) feedback that is based on Qprecoding dimensions, wherein: there is a mapping between the P_(CSIRS)CSI-RS ports and the Q precoding dimensions, and P_(CSIRS)≠Q; measuringthe P_(CSIRS) CSI-RS ports; determining a measurement for the Qprecoding dimensions based on the mapping and the measurement for theP_(CSIRS) CSI-RS ports; determining a CSI feedback based on themeasurement for the Q precoding dimensions; and transmitting, over anuplink (UL) channel, the determined CSI feedback.

Other technical features may be readily apparent to one skilled in theart from the following figures, descriptions, and claims.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document. The term “couple” and its derivativesrefer to any direct or indirect communication between two or moreelements, whether or not those elements are in physical contact with oneanother. The terms “transmit,” “receive,” and “communicate,” as well asderivatives thereof, encompass both direct and indirect communication.The terms “include” and “comprise,” as well as derivatives thereof, meaninclusion without limitation. The term “or” is inclusive, meaningand/or. The phrase “associated with,” as well as derivatives thereof,means to include, be included within, interconnect with, contain, becontained within, connect to or with, couple to or with, be communicablewith, cooperate with, interleave, juxtapose, be proximate to, be boundto or with, have, have a property of, have a relationship to or with, orthe like. The term “controller” means any device, system or part thereofthat controls at least one operation. Such a controller may beimplemented in hardware or a combination of hardware and software and/orfirmware. The functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely. Thephrase “at least one of,” when used with a list of items, means thatdifferent combinations of one or more of the listed items may be used,and only one item in the list may be needed. For example, “at least oneof: A, B, and C” includes any of the following combinations: A, B, C, Aand B, A and C, B and C, and A and B and C.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for other certain words and phrases are provided throughoutthis patent document. Those of ordinary skill in the art shouldunderstand that in many if not most instances, such definitions apply toprior as well as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates an example wireless network according to embodimentsof the present disclosure;

FIG. 2 illustrates an example gNB according to embodiments of thepresent disclosure;

FIG. 3 illustrates an example UE according to embodiments of the presentdisclosure;

FIG. 4A illustrates a high-level diagram of an orthogonal frequencydivision multiple access transmit path according to embodiments of thepresent disclosure;

FIG. 4B illustrates a high-level diagram of an orthogonal frequencydivision multiple access receive path according to embodiments of thepresent disclosure;

FIG. 5 illustrates a transmitter block diagram for a PDSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 6 illustrates a receiver block diagram for a PDSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 7 illustrates a transmitter block diagram for a PUSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 8 illustrates a receiver block diagram for a PUSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 9 illustrates an example network configuration according toembodiments of the present disclosure;

FIG. 10 illustrates an example multiplexing of two slices according toembodiments of the present disclosure;

FIG. 11 illustrates an example antenna blocks according to embodimentsof the present disclosure;

FIG. 12 illustrates an antenna port layout according to embodiments ofthe present disclosure;

FIG. 13 illustrates a 3D grid of oversampled DFT beams according toembodiments of the present disclosure;

FIG. 14 illustrates an example mapping of CSI-RS ports to index pairsaccording to embodiments of the present disclosure;

FIG. 15 illustrates a flow chart of a method for operating a UEaccording to embodiments of the present disclosure; and

FIG. 16 illustrates a flow chart of a method for operating a BSaccording to embodiments of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 through FIG. 16 , discussed below, and the various embodimentsused to describe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system or device.

The following documents and standards descriptions are herebyincorporated by reference into the present disclosure as if fully setforth herein: 3GPP TS 36.211 v16.3.0, “E-UTRA, Physical channels andmodulation” (herein “REF 1”); 3GPP TS 36.212 v16.3.0, “E-UTRA,Multiplexing and Channel coding” (herein “REF 2”); 3GPP TS 36.213v16.3.0, “E-UTRA, Physical Layer Procedures” (herein “REF 3”); 3GPP TS36.321 v16.3.0, “E-UTRA, Medium Access Control (MAC) protocolspecification” (herein “REF 4”); 3GPP TS 36.331 v16.3.0, “E-UTRA, RadioResource Control (RRC) protocol specification” (herein “REF 5”); 3GPP TR22.891 v14.2.0 (herein “REF 6”); 3GPP TS 38.212 v16.3.0, “E-UTRA, NR,Multiplexing and channel coding” (herein “REF 7”); 3GPP TS 38.214v16.3.0, “E-UTRA, NR, Physical layer procedures for data” (herein “REF8”); and 3GPP TS 38.213 v16.3.0, “E-UTRA, NR, Physical Layer Proceduresfor control” (herein “REF 9”).

Aspects, features, and advantages of the disclosure are readily apparentfrom the following detailed description, simply by illustrating a numberof particular embodiments and implementations, including the best modecontemplated for carrying out the disclosure. The disclosure is alsocapable of other and different embodiments, and its several details canbe modified in various obvious respects, all without departing from thespirit and scope of the disclosure. Accordingly, the drawings anddescription are to be regarded as illustrative in nature, and not asrestrictive. The disclosure is illustrated by way of example, and not byway of limitation, in the figures of the accompanying drawings.

In the following, for brevity, both FDD and TDD are considered as theduplex method for both DL and UL signaling.

Although exemplary descriptions and embodiments to follow assumeorthogonal frequency division multiplexing (OFDM) or orthogonalfrequency division multiple access (OFDMA), the present disclosure canbe extended to other OFDM-based transmission waveforms or multipleaccess schemes such as filtered OFDM (F-OFDM).

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a “beyond 4G network” or a“post LTE system.”

The 5G communication system is considered to be implemented in higherfrequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higherdata rates or in lower frequency bands, such as below 6 GHz, to enablerobust coverage and mobility support. To decrease propagation loss ofthe radio waves and increase the transmission coverage, the beamforming,massive multiple-input multiple-output (MIMO), full dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques and the like are discussed in 5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud radioaccess networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul communication, moving network,cooperative communication, coordinated multi-points (CoMP) transmissionand reception, interference mitigation and cancellation and the like.

FIGS. 1-4B below describe various embodiments implemented in wirelesscommunications systems and with the use of orthogonal frequency divisionmultiplexing (OFDM) or orthogonal frequency division multiple access(OFDMA) communication techniques. The descriptions of FIGS. 1-3 are notmeant to imply physical or architectural limitations to the manner inwhich different embodiments may be implemented. Different embodiments ofthe present disclosure may be implemented in any suitably-arrangedcommunications system. The present disclosure covers several componentswhich can be used in conjunction or in combination with one another, orcan operate as standalone schemes.

FIG. 1 illustrates an example wireless network according to embodimentsof the present disclosure. The embodiment of the wireless network shownin FIG. 1 is for illustration only. Other embodiments of the wirelessnetwork 100 could be used without departing from the scope of thisdisclosure.

As shown in FIG. 1 , the wireless network includes a gNB 101, a gNB 102,and a gNB 103. The gNB 101 communicates with the gNB 102 and the gNB103. The gNB 101 also communicates with at least one network 130, suchas the Internet, a proprietary Internet Protocol (IP) network, or otherdata network.

The gNB 102 provides wireless broadband access to the network 130 for afirst plurality of user equipments (UEs) within a coverage area 120 ofthe gNB 102. The first plurality of UEs includes a UE 111, which may belocated in a small business; a UE 112, which may be located in anenterprise (E); a UE 113, which may be located in a WiFi hotspot (HS); aUE 114, which may be located in a first residence (R); a UE 115, whichmay be located in a second residence (R); and a UE 116, which may be amobile device (M), such as a cell phone, a wireless laptop, a wirelessPDA, or the like. The gNB 103 provides wireless broadband access to thenetwork 130 for a second plurality of UEs within a coverage area 125 ofthe gNB 103. The second plurality of UEs includes the UE 115 and the UE116. In some embodiments, one or more of the gNBs 101-103 maycommunicate with each other and with the UEs 111-116 using 5G, LTE,LTE-A, WiMAX, WiFi, or other wireless communication techniques.

Depending on the network type, the term “base station” or “BS” can referto any component (or collection of components) configured to providewireless access to a network, such as transmit point (TP),transmit-receive point (TRP), an enhanced base station (eNodeB or eNB),a 5G base station (gNB), a macrocell, a femtocell, a WiFi access point(AP), or other wirelessly enabled devices. Base stations may providewireless access in accordance with one or more wireless communicationprotocols, e.g., 5G 3GPP new radio interface/access (NR), long termevolution (LTE), LTE advanced (LTE-A), high speed packet access (HSPA),Wi-Fi 802.11a/b/g/n/ac, etc. For the sake of convenience, the terms “BS”and “TRP” are used interchangeably in this patent document to refer tonetwork infrastructure components that provide wireless access to remoteterminals. Also, depending on the network type, the term “userequipment” or “UE” can refer to any component such as “mobile station,”“subscriber station,” “remote terminal,” “wireless terminal,” “receivepoint,” or “user device.” For the sake of convenience, the terms “userequipment” and “UE” are used in this patent document to refer to remotewireless equipment that wirelessly accesses a BS, whether the UE is amobile device (such as a mobile telephone or smartphone) or is normallyconsidered a stationary device (such as a desktop computer or vendingmachine).

Dotted lines show the approximate extents of the coverage areas 120 and125, which are shown as approximately circular for the purposes ofillustration and explanation only. It should be clearly understood thatthe coverage areas associated with gNBs, such as the coverage areas 120and 125, may have other shapes, including irregular shapes, dependingupon the configuration of the gNBs and variations in the radioenvironment associated with natural and man-made obstructions.

As described in more detail below, one or more of the UEs 111-116include circuitry, programing, or a combination thereof, for receivingconfiguration information for at least one channel state informationreference signal (CSI-RS) resource that comprises P_(CSIRS) CSI-RSports; receiving configuration information for channel state information(CSI) feedback that is based on Q precoding dimensions, wherein: thereis a mapping between the P_(CSIRS) CSI-RS ports and the Q precodingdimensions, and P_(CSIRS)≠Q measuring the P_(CSIRS) CSI-RS ports;determining a measurement for the Q precoding dimensions based on themapping and the measurement for the P_(CSIRS) CSI-RS ports; determininga CSI feedback based on the measurement for the Q precoding dimensions;and transmitting, over an uplink (UL) channel, the determined CSIfeedback, and one or more of the gNBs 101-103 includes circuitry,programing, or a combination thereof, for generating configurationinformation for at least one channel state information reference signal(CSI-RS) resource that comprises P_(CSIRS) CSI-RS ports; generatingconfiguration information for channel state information (CSI) feedbackthat is based on Q precoding dimensions, wherein: there is a mappingbetween the P_(CSIRS) CSI-RS ports and the Q precoding dimensions, andP_(CSIRS)≠Q; transmitting the configuration information for the at leastone CSI-RS resource; transmitting the configuration information for theCSI feedback; transmitting the at least one CSI-RS resource from theP_(CSIRS) CSI-RS ports; and receiving, over an uplink (UL) channel, theCSI feedback; wherein: the CSI feedback is based on the Q precodingdimensions, and the Q precoding dimensions are based on the mapping andthe P_(CSIRS) CSI-RS ports.

Although FIG. 1 illustrates one example of a wireless network, variouschanges may be made to FIG. 1 . For example, the wireless network couldinclude any number of gNBs and any number of UEs in any suitablearrangement. Also, the gNB 101 could communicate directly with anynumber of UEs and provide those UEs with wireless broadband access tothe network 130. Similarly, each gNB 102-103 could communicate directlywith the network 130 and provide UEs with direct wireless broadbandaccess to the network 130. Further, the gNBs 101, 102, and/or 103 couldprovide access to other or additional external networks, such asexternal telephone networks or other types of data networks.

FIG. 2 illustrates an example gNB 102 according to embodiments of thepresent disclosure. The embodiment of the gNB 102 illustrated in FIG. 2is for illustration only, and the gNBs 101 and 103 of FIG. 1 could havethe same or similar configuration. However, gNBs come in a wide varietyof configurations, and FIG. 2 does not limit the scope of thisdisclosure to any particular implementation of a gNB.

As shown in FIG. 2 , the gNB 102 includes multiple antennas 205 a-205 n,multiple RF transceivers 210 a-210 n, transmit (TX) processing circuitry215, and receive (RX) processing circuitry 220. The gNB 102 alsoincludes a controller/processor 225, a memory 230, and a backhaul ornetwork interface 235.

The RF transceivers 210 a-210 n receive, from the antennas 205 a-205 n,incoming RF signals, such as signals transmitted by UEs in the network100. The RF transceivers 210 a-210 n down-convert the incoming RFsignals to generate IF or baseband signals. The IF or baseband signalsare sent to the RX processing circuitry 220, which generates processedbaseband signals by filtering, decoding, and/or digitizing the basebandor IF signals. The RX processing circuitry 220 transmits the processedbaseband signals to the controller/processor 225 for further processing.

The TX processing circuitry 215 receives analog or digital data (such asvoice data, web data, e-mail, or interactive video game data) from thecontroller/processor 225. The TX processing circuitry 215 encodes,multiplexes, and/or digitizes the outgoing baseband data to generateprocessed baseband or IF signals. The RF transceivers 210 a-210 nreceive the outgoing processed baseband or IF signals from the TXprocessing circuitry 215 and up-converts the baseband or IF signals toRF signals that are transmitted via the antennas 205 a-205 n.

The controller/processor 225 can include one or more processors or otherprocessing devices that control the overall operation of the gNB 102.For example, the controller/processor 225 could control the reception offorward channel signals and the transmission of reverse channel signalsby the RF transceivers 210 a-210 n, the RX processing circuitry 220, andthe TX processing circuitry 215 in accordance with well-knownprinciples. The controller/processor 225 could support additionalfunctions as well, such as more advanced wireless communicationfunctions.

For instance, the controller/processor 225 could support beam forming ordirectional routing operations in which outgoing signals from multipleantennas 205 a-205 n are weighted differently to effectively steer theoutgoing signals in a desired direction. Any of a wide variety of otherfunctions could be supported in the gNB 102 by the controller/processor225.

The controller/processor 225 is also capable of executing programs andother processes resident in the memory 230, such as an OS. Thecontroller/processor 225 can move data into or out of the memory 230 asrequired by an executing process.

The controller/processor 225 is also coupled to the backhaul or networkinterface 235. The backhaul or network interface 235 allows the gNB 102to communicate with other devices or systems over a backhaul connectionor over a network. The interface 235 could support communications overany suitable wired or wireless connection(s). For example, when the gNB102 is implemented as part of a cellular communication system (such asone supporting 5G, LTE, or LTE-A), the interface 235 could allow the gNB102 to communicate with other gNBs over a wired or wireless backhaulconnection. When the gNB 102 is implemented as an access point, theinterface 235 could allow the gNB 102 to communicate over a wired orwireless local area network or over a wired or wireless connection to alarger network (such as the Internet). The interface 235 includes anysuitable structure supporting communications over a wired or wirelessconnection, such as an Ethernet or RF transceiver.

The memory 230 is coupled to the controller/processor 225. Part of thememory 230 could include a RAM, and another part of the memory 230 couldinclude a Flash memory or other ROM.

Although FIG. 2 illustrates one example of gNB 102, various changes maybe made to FIG. 2 . For example, the gNB 102 could include any number ofeach component shown in FIG. 2 . As a particular example, an accesspoint could include a number of interfaces 235, and thecontroller/processor 225 could support routing functions to route databetween different network addresses. As another particular example,while shown as including a single instance of TX processing circuitry215 and a single instance of RX processing circuitry 220, the gNB 102could include multiple instances of each (such as one per RFtransceiver). Also, various components in FIG. 2 could be combined,further subdivided, or omitted and additional components could be addedaccording to particular needs.

FIG. 3 illustrates an example UE 116 according to embodiments of thepresent disclosure. The embodiment of the UE 116 illustrated in FIG. 3is for illustration only, and the UEs 111-115 of FIG. 1 could have thesame or similar configuration. However, UEs come in a wide variety ofconfigurations, and FIG. 3 does not limit the scope of this disclosureto any particular implementation of a UE.

As shown in FIG. 3 , the UE 116 includes an antenna 305, a radiofrequency (RF) transceiver 310, TX processing circuitry 315, amicrophone 320, and receive (RX) processing circuitry 325. The UE 116also includes a speaker 330, a processor 340, an input/output (I/O)interface (IF) 345, a touchscreen 350, a display 355, and a memory 360.The memory 360 includes an operating system (OS) 361 and one or moreapplications 362.

The RF transceiver 310 receives, from the antenna 305, an incoming RFsignal transmitted by a gNB of the network 100. The RF transceiver 310down-converts the incoming RF signal to generate an intermediatefrequency (IF) or baseband signal. The IF or baseband signal is sent tothe RX processing circuitry 325, which generates a processed basebandsignal by filtering, decoding, and/or digitizing the baseband or IFsignal. The RX processing circuitry 325 transmits the processed basebandsignal to the speaker 330 (such as for voice data) or to the processor340 for further processing (such as for web browsing data).

The TX processing circuitry 315 receives analog or digital voice datafrom the microphone 320 or other outgoing baseband data (such as webdata, e-mail, or interactive video game data) from the processor 340.The TX processing circuitry 315 encodes, multiplexes, and/or digitizesthe outgoing baseband data to generate a processed baseband or IFsignal. The RF transceiver 310 receives the outgoing processed basebandor IF signal from the TX processing circuitry 315 and up-converts thebaseband or IF signal to an RF signal that is transmitted via theantenna 305.

The processor 340 can include one or more processors or other processingdevices and execute the OS 361 stored in the memory 360 in order tocontrol the overall operation of the UE 116. For example, the processor340 could control the reception of forward channel signals and thetransmission of reverse channel signals by the RF transceiver 310, theRX processing circuitry 325, and the TX processing circuitry 315 inaccordance with well-known principles. In some embodiments, theprocessor 340 includes at least one microprocessor or microcontroller.

The processor 340 is also capable of executing other processes andprograms resident in the memory 360, such as processes for receivingconfiguration information for at least one channel state informationreference signal (CSI-RS) resource that comprises P_(CSIRS) CSI-RSports; receiving configuration information for channel state information(CSI) feedback that is based on Q precoding dimensions, wherein: thereis a mapping between the P_(CSIRS) CSI-RS ports and the Q precodingdimensions, and P_(CSIRS)≠Q; measuring the P_(CSIRS) CSI-RS ports;determining a measurement for the Q precoding dimensions based on themapping and the measurement for the P_(CSIRS) CSI-RS ports; determininga CSI feedback based on the measurement for the Q precoding dimensions;and transmitting, over an uplink (UL) channel, the determined CSIfeedback. The processor 340 can move data into or out of the memory 360as required by an executing process. In some embodiments, the processor340 is configured to execute the applications 362 based on the OS 361 orin response to signals received from gNBs or an operator. The processor340 is also coupled to the I/O interface 345, which provides the UE 116with the ability to connect to other devices, such as laptop computersand handheld computers. The I/O interface 345 is the communication pathbetween these accessories and the processor 340.

The processor 340 is also coupled to the touchscreen 350 and the display355. The operator of the UE 116 can use the touchscreen 350 to enterdata into the UE 116. The display 355 may be a liquid crystal display,light emitting diode display, or other display capable of rendering textand/or at least limited graphics, such as from web sites.

The memory 360 is coupled to the processor 340. Part of the memory 360could include a random access memory (RAM), and another part of thememory 360 could include a Flash memory or other read-only memory (ROM).

Although FIG. 3 illustrates one example of UE 116, various changes maybe made to FIG. 3 . For example, various components in FIG. 3 could becombined, further subdivided, or omitted and additional components couldbe added according to particular needs. As a particular example, theprocessor 340 could be divided into multiple processors, such as one ormore central processing units (CPUs) and one or more graphics processingunits (GPUs). Also, while FIG. 3 illustrates the UE 116 configured as amobile telephone or smartphone, UEs could be configured to operate asother types of mobile or stationary devices.

FIG. 4A is a high-level diagram of transmit path circuitry. For example,the transmit path circuitry may be used for an orthogonal frequencydivision multiple access (OFDMA) communication. FIG. 4B is a high-leveldiagram of receive path circuitry. For example, the receive pathcircuitry may be used for an orthogonal frequency division multipleaccess (OFDMA) communication. In FIGS. 4A and 4B, for downlinkcommunication, the transmit path circuitry may be implemented in a basestation (gNB) 102 or a relay station, and the receive path circuitry maybe implemented in a user equipment (e.g., user equipment 116 of FIG. 1). In other examples, for uplink communication, the receive pathcircuitry 450 may be implemented in a base station (e.g., gNB 102 ofFIG. 1 ) or a relay station, and the transmit path circuitry may beimplemented in a user equipment (e.g., user equipment 116 of FIG. 1 ).

Transmit path circuitry comprises channel coding and modulation block405, serial-to-parallel (S-to-P) block 410, Size N Inverse Fast FourierTransform (IFFT) block 415, parallel-to-serial (P-to-S) block 420, addcyclic prefix block 425, and up-converter (UC) 430. Receive pathcircuitry 450 comprises down-converter (DC) 455, remove cyclic prefixblock 460, serial-to-parallel (S-to-P) block 465, Size N Fast FourierTransform (FFT) block 470, parallel-to-serial (P-to-S) block 475, andchannel decoding and demodulation block 480.

At least some of the components in FIGS. 4A 400 and 4B 450 may beimplemented in software, while other components may be implemented byconfigurable hardware or a mixture of software and configurablehardware. In particular, it is noted that the FFT blocks and the IFFTblocks described in this disclosure document may be implemented asconfigurable software algorithms, where the value of Size N may bemodified according to the implementation.

Furthermore, although this disclosure is directed to an embodiment thatimplements the Fast Fourier Transform and the Inverse Fast FourierTransform, this is by way of illustration only and may not be construedto limit the scope of the disclosure. It may be appreciated that in analternate embodiment of the present disclosure, the Fast FourierTransform functions and the Inverse Fast Fourier Transform functions mayeasily be replaced by discrete Fourier transform (DFT) functions andinverse discrete Fourier transform (IDFT) functions, respectively. Itmay be appreciated that for DFT and IDFT functions, the value of the Nvariable may be any integer number (i.e., 1, 4, 3, 4, etc.), while forFFT and IFFT functions, the value of the N variable may be any integernumber that is a power of two (i.e., 1, 2, 4, 8, 16, etc.).

In transmit path circuitry 400, channel coding and modulation block 405receives a set of information bits, applies coding (e.g., LDPC coding)and modulates (e.g., quadrature phase shift keying (QPSK) or quadratureamplitude modulation (QAM)) the input bits to produce a sequence offrequency-domain modulation symbols. Serial-to-parallel block 410converts (i.e., de-multiplexes) the serial modulated symbols to paralleldata to produce N parallel symbol streams where N is the IFFT/FFT sizeused in BS 102 and UE 116. Size N IFFT block 415 then performs an IFFToperation on the N parallel symbol streams to produce time-domain outputsignals. Parallel-to-serial block 420 converts (i.e., multiplexes) theparallel time-domain output symbols from Size N IFFT block 415 toproduce a serial time-domain signal. Add cyclic prefix block 425 theninserts a cyclic prefix to the time-domain signal. Finally, up-converter430 modulates (i.e., up-converts) the output of add cyclic prefix block425 to RF frequency for transmission via a wireless channel. The signalmay also be filtered at baseband before conversion to RF frequency.

The transmitted RF signal arrives at the UE 116 after passing throughthe wireless channel, and reverse operations to those at gNB 102 areperformed. Down-converter 455 down-converts the received signal tobaseband frequency and removes cyclic prefix block 460, and removes thecyclic prefix to produce the serial time-domain baseband signal.Serial-to-parallel block 465 converts the time-domain baseband signal toparallel time-domain signals. Size N FFT block 470 then performs an FFTalgorithm to produce N parallel frequency-domain signals.Parallel-to-serial block 475 converts the parallel frequency-domainsignals to a sequence of modulated data symbols. Channel decoding anddemodulation block 480 demodulates and then decodes the modulatedsymbols to recover the original input data stream.

Each of gNBs 101-103 may implement a transmit path that is analogous totransmitting in the downlink to user equipment 111-116 and may implementa receive path that is analogous to receiving in the uplink from userequipment 111-116. Similarly, each one of user equipment 111-116 mayimplement a transmit path corresponding to the architecture fortransmitting in the uplink to gNB s 101-103 and may implement a receivepath corresponding to the architecture for receiving in the downlinkfrom gNBs 101-103.

5G communication system use cases have been identified and described.Those use cases can be roughly categorized into three different groups.In one example, enhanced mobile broadband (eMBB) is determined to dowith high bits/sec requirement, with less stringent latency andreliability requirements. In another example, ultra reliable and lowlatency (URLL) is determined with less stringent bits/sec requirement.In yet another example, massive machine type communication (mMTC) isdetermined that a number of devices can be as many as 100,000 to 1million per km2, but the reliability/throughput/latency requirementcould be less stringent. This scenario may also involve power efficiencyrequirement as well, in that the battery consumption may be minimized aspossible.

A communication system includes a downlink (DL) that conveys signalsfrom transmission points such as base stations (BSs) or NodeBs to userequipments (UEs) and an Uplink (UL) that conveys signals from UEs toreception points such as NodeBs. A UE, also commonly referred to as aterminal or a mobile station, may be fixed or mobile and may be acellular phone, a personal computer device, or an automated device. AneNodeB, which is generally a fixed station, may also be referred to asan access point or other equivalent terminology. For LTE systems, aNodeB is often referred as an eNodeB.

In a communication system, such as LTE system, DL signals can includedata signals conveying information content, control signals conveying DLcontrol information (DCI), and reference signals (RS) that are alsoknown as pilot signals. An eNodeB transmits data information through aphysical DL shared channel (PDSCH). An eNodeB transmits DCI through aphysical DL control channel (PDCCH) or an Enhanced PDCCH (EPDCCH).

An eNodeB transmits acknowledgement information in response to datatransport block (TB) transmission from a UE in a physical hybrid ARQindicator channel (PHICH). An eNodeB transmits one or more of multipletypes of RS including a UE-common RS (CRS), a channel state informationRS (CSI-RS), or a demodulation RS (DMRS). A CRS is transmitted over a DLsystem bandwidth (BW) and can be used by UEs to obtain a channelestimate to demodulate data or control information or to performmeasurements. To reduce CRS overhead, an eNodeB may transmit a CSI-RSwith a smaller density in the time and/or frequency domain than a CRS.DMRS can be transmitted only in the BW of a respective PDSCH or EPDCCHand a UE can use the DMRS to demodulate data or control information in aPDSCH or an EPDCCH, respectively. A transmission time interval for DLchannels is referred to as a subframe and can have, for example,duration of 1 millisecond.

DL signals also include transmission of a logical channel that carriessystem control information. A BCCH is mapped to either a transportchannel referred to as a broadcast channel (BCH) when the DL signalsconvey a master information block (MIB) or to a DL shared channel(DL-SCH) when the DL signals convey a System Information Block (SIB).Most system information is included in different SIBs that aretransmitted using DL-SCH. A presence of system information on a DL-SCHin a subframe can be indicated by a transmission of a correspondingPDCCH conveying a codeword with a cyclic redundancy check (CRC)scrambled with system information RNTI (SI-RNTI). Alternatively,scheduling information for a SIB transmission can be provided in anearlier SIB and scheduling information for the first SIB (SIB-1) can beprovided by the MIB.

DL resource allocation is performed in a unit of subframe and a group ofphysical resource blocks (PRBs). A transmission BW includes frequencyresource units referred to as resource blocks (RBs). Each RB includesN_(sc) ^(RB) sub-carriers, or resource elements (REs), such as 12 REs. Aunit of one RB over one subframe is referred to as a PRB. A UE can beallocated M_(PDSCH) RBs for a total of M_(sc) ^(PDSCH)=M_(PDSCH)·N_(sc)^(RB) REs for the PDSCH transmission BW.

UL signals can include data signals conveying data information, controlsignals conveying UL control information (UCI), and UL RS. UL RSincludes DMRS and Sounding RS (SRS). A UE transmits DMRS only in a BW ofa respective PUSCH or PUCCH. An eNodeB can use a DMRS to demodulate datasignals or UCI signals. A UE transmits SRS to provide an eNodeB with anUL CSI. A UE transmits data information or UCI through a respectivephysical UL shared channel (PUSCH) or a Physical UL control channel(PUCCH). If a UE needs to transmit data information and UCI in a same ULsubframe, the UE may multiplex both in a PUSCH. UCI includes HybridAutomatic Repeat request acknowledgement (HARQ-ACK) information,indicating correct (ACK) or incorrect (NACK) detection for a data TB ina PDSCH or absence of a PDCCH detection (DTX), scheduling request (SR)indicating whether a UE has data in the UE's buffer, rank indicator(RI), and channel state information (CSI) enabling an eNodeB to performlink adaptation for PDSCH transmissions to a UE. HARQ-ACK information isalso transmitted by a UE in response to a detection of a PDCCH/EPDCCHindicating a release of semi-persistently scheduled PDSCH.

An UL subframe includes two slots. Each slot includes N_(symb) ^(UL)symbols for transmitting data information, UCI, DMRS, or SRS. Afrequency resource unit of an UL system BW is a RB. A UE is allocatedN_(RB) RBs for a total of N_(RB)·N_(sc) ^(RB) REs for a transmission BW.For a PUCCH, N_(RB)=1. A last subframe symbol can be used to multiplexSRS transmissions from one or more UEs. A number of subframe symbolsthat are available for data/UCI/DMRS transmission isN_(symb)=2·(M_(symb) ^(UL)−1)−N_(SRS), where N_(SRS)=1 if a lastsubframe symbol is used to transmit SRS and N_(SRS)=0 otherwise.

FIG. 5 illustrates a transmitter block diagram 500 for a PDSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the transmitter block diagram 500 illustrated in FIG. 5 isfor illustration only. One or more of the components illustrated in FIG.5 can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 5 does not limit the scope of this disclosure to anyparticular implementation of the transmitter block diagram 500.

As shown in FIG. 5 , information bits 510 are encoded by encoder 520,such as a turbo encoder, and modulated by modulator 530, for exampleusing quadrature phase shift keying (QPSK) modulation. A serial toparallel (S/P) converter 540 generates M modulation symbols that aresubsequently provided to a mapper 550 to be mapped to REs selected by atransmission BW selection unit 555 for an assigned PDSCH transmissionBW, unit 560 applies an Inverse fast Fourier transform (IFFT), theoutput is then serialized by a parallel to serial (P/S) converter 570 tocreate a time domain signal, filtering is applied by filter 580, and asignal transmitted 590. Additional functionalities, such as datascrambling, cyclic prefix insertion, time windowing, interleaving, andothers are well known in the art and are not shown for brevity.

FIG. 6 illustrates a receiver block diagram 600 for a PDSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the diagram 600 illustrated in FIG. 6 is for illustrationonly. One or more of the components illustrated in FIG. 6 can beimplemented in specialized circuitry configured to perform the notedfunctions or one or more of the components can be implemented by one ormore processors executing instructions to perform the noted functions.FIG. 6 does not limit the scope of this disclosure to any particularimplementation of the diagram 600.

As shown in FIG. 6 , a received signal 610 is filtered by filter 620,REs 630 for an assigned reception BW are selected by BW selector 635,unit 640 applies a fast Fourier transform (FFT), and an output isserialized by a parallel-to-serial converter 650. Subsequently, ademodulator 660 coherently demodulates data symbols by applying achannel estimate obtained from a DMRS or a CRS (not shown), and adecoder 670, such as a turbo decoder, decodes the demodulated data toprovide an estimate of the information data bits 680. Additionalfunctionalities such as time-windowing, cyclic prefix removal,de-scrambling, channel estimation, and de-interleaving are not shown forbrevity.

FIG. 7 illustrates a transmitter block diagram 700 for a PUSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the block diagram 700 illustrated in FIG. 7 is forillustration only. One or more of the components illustrated in FIG. 5can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 7 does not limit the scope of this disclosure to anyparticular implementation of the block diagram 700.

As shown in FIG. 7 , information data bits 710 are encoded by encoder720, such as a turbo encoder, and modulated by modulator 730. A discreteFourier transform (DFT) unit 740 applies a DFT on the modulated databits, REs 750 corresponding to an assigned PUSCH transmission BW areselected by transmission BW selection unit 755, unit 760 applies an IFFTand, after a cyclic prefix insertion (not shown), filtering is appliedby filter 770 and a signal transmitted 780.

FIG. 8 illustrates a receiver block diagram 800 for a PUSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the block diagram 800 illustrated in FIG. 8 is forillustration only. One or more of the components illustrated in FIG. 8can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 8 does not limit the scope of this disclosure to anyparticular implementation of the block diagram 800.

As shown in FIG. 8 , a received signal 810 is filtered by filter 820.Subsequently, after a cyclic prefix is removed (not shown), unit 830applies a FFT, REs 840 corresponding to an assigned PUSCH reception BWare selected by a reception BW selector 845, unit 850 applies an inverseDFT (IDFT), a demodulator 860 coherently demodulates data symbols byapplying a channel estimate obtained from a DMRS (not shown), a decoder870, such as a turbo decoder, decodes the demodulated data to provide anestimate of the information data bits 880.

In next generation cellular systems, various use cases are envisionedbeyond the capabilities of LTE system. Termed 5G or the fifth generationcellular system, a system capable of operating at sub-6 GHz and above-6GHz (for example, in mmWave regime) becomes one of the requirements. In3GPP TR 22.891, 74 5G use cases have been identified and described;those use cases can be roughly categorized into three different groups.A first group is termed “enhanced mobile broadband (eMBB),” targeted tohigh data rate services with less stringent latency and reliabilityrequirements. A second group is termed “ultra-reliable and low latency(URLL)” targeted for applications with less stringent data raterequirements, but less tolerant to latency. A third group is termed“massive MTC (mMTC)” targeted for large number of low-power deviceconnections such as 1 million per km² with less stringent thereliability, data rate, and latency requirements.

FIG. 9 illustrates an example network configuration 900 according toembodiments of the present disclosure. The embodiment of the networkconfiguration 900 illustrated in FIG. 9 is for illustration only. FIG. 9does not limit the scope of this disclosure to any particularimplementation of the configuration 900.

In order for the 5G network to support such diverse services withdifferent quality of services (QoS), one scheme has been identified in3GPP specification, called network slicing.

As shown in FIG. 9 , an operator's network 910 includes a number ofradio access network(s) 920 (RAN(s)) that are associated with networkdevices such as gNBs 930 a and 930 b, small cell base stations(femto/pico gNBs or Wi-Fi access points) 935 a and 935 b. The network910 can support various services, each represented as a slice.

In the example, an URLL slice 940 a serves UEs requiring URLL servicessuch as cars 945 b, trucks 945 c, smart watches 945 a, and smart glasses945 d. Two mMTC slices 950 a and 950 b serve UEs requiring mMTC servicessuch as power meters 955 a, and temperature control box 955 b. One eMBBslice 960 a serves UEs requiring eMBB services such as cells phones 965a, laptops 965 b, and tablets 965 c. A device configured with two slicescan also be envisioned.

To utilize PHY resources efficiently and multiplex various slices (withdifferent resource allocation schemes, numerologies, and schedulingstrategies) in DL-SCH, a flexible and self-contained frame or subframedesign is utilized.

FIG. 10 illustrates an example multiplexing of two slices 1000 accordingto embodiments of the present disclosure. The embodiment of themultiplexing of two slices 1000 illustrated in FIG. 10 is forillustration only. One or more of the components illustrated in FIG. 10can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 10 does not limit the scope of this disclosure to anyparticular implementation of the multiplexing of two slices 1000.

Two exemplary instances of multiplexing two slices within a commonsubframe or frame are depicted in FIG. 10 . In these exemplaryembodiments, a slice can be composed of one or two transmissioninstances where one transmission instance includes a control (CTRL)component (e.g., 1020 a, 1060 a, 1060 b, 1020 b, or 1060 c) and a datacomponent (e.g., 1030 a, 1070 a, 1070 b, 1030 b, or 1070 c). Inembodiment 1010, the two slices are multiplexed in frequency domainwhereas in embodiment 1050, the two slices are multiplexed in timedomain.

The 3GPP NR specification supports up to 32 CSI-RS antenna ports whichenable a gNB to be equipped with a large number of antenna elements(such as 64 or 128). In this case, a plurality of antenna elements ismapped onto one CSI-RS port. For next generation cellular systems suchas 5G, the maximum number of CSI-RS ports can either remain the same orincrease.

FIG. 11 illustrates an example antenna blocks 1100 according toembodiments of the present disclosure. The embodiment of the antennablocks 1100 illustrated in FIG. 11 is for illustration only. FIG. 11does not limit the scope of this disclosure to any particularimplementation of the antenna blocks 1100.

For mmWave bands, although the number of antenna elements can be largerfor a given form factor, the number of CSI-RS ports—which can correspondto the number of digitally precoded ports—tends to be limited due tohardware constraints (such as the feasibility to install a large numberof ADCs/DACs at mmWave frequencies) as illustrated in FIG. 11 . In thiscase, one CSI-RS port is mapped onto a large number of antenna elementswhich can be controlled by a bank of analog phase shifters. One CSI-RSport can then correspond to one sub-array which produces a narrow analogbeam through analog beamforming. This analog beam can be configured tosweep across a wider range of angles by varying the phase shifter bankacross symbols or subframes. The number of sub-arrays (equal to thenumber of RF chains) is the same as the number of CSI-RS portsN_(CSI-PORT). A digital beamforming unit performs a linear combinationacross N_(CSI-PORT) analog beams to further increase precoding gain.While analog beams are wideband (hence not frequency-selective), digitalprecoding can be varied across frequency sub-bands or resource blocks.

To enable digital precoding, efficient design of CSI-RS is a crucialfactor. For this reason, three types of CSI reporting mechanismscorresponding to three types of CSI-RS measurement behavior aresupported, for example, “CLASS A” CSI reporting which corresponds tonon-precoded CSI-RS, “CLASS B” reporting with K=1 CSI-RS resource whichcorresponds to UE-specific beamformed CSI-RS, and “CLASS B” reportingwith K>1 CSI-RS resources which corresponds to cell-specific beamformedCSI-RS.

For non-precoded (NP) CSI-RS, a cell-specific one-to-one mapping betweenCSI-RS port and TXRU is utilized. Different CSI-RS ports have the samewide beam width and direction and hence generally cell wide coverage.For beamformed CSI-RS, beamforming operation, either cell-specific orUE-specific, is applied on a non-zero-power (NZP) CSI-RS resource (e.g.,comprising multiple ports). At least at a given time/frequency, CSI-RSports have narrow beam widths and hence not cell wide coverage, and atleast from the gNB perspective. At least some CSI-RS port-resourcecombinations have different beam directions.

In scenarios where DL long-term channel statistics can be measuredthrough UL signals at a serving eNodeB, UE-specific BF CSI-RS can bereadily used. This is typically feasible when UL-DL duplex distance issufficiently small. When this condition does not hold, however, some UEfeedback is necessary for the eNodeB to obtain an estimate of DLlong-term channel statistics (or any of representation thereof). Tofacilitate such a procedure, a first BF CSI-RS transmitted withperiodicity T1 (ms) and a second NP CSI-RS transmitted with periodicityT2 (ms), where T1≤T2. This approach is termed hybrid CSI-RS. Theimplementation of hybrid CSI-RS is largely dependent on the definitionof CSI process and NZP CSI-RS resource.

In the 3GPP LTE specification, MIMO has been identified as an essentialfeature in order to achieve high system throughput requirements and itwill continue to be the same in NR. One of the key components of a MIMOtransmission scheme is the accurate CSI acquisition at the eNB (or TRP).For MU-MIMO, in particular, the availability of accurate CSI isnecessary in order to guarantee high MU performance. For TDD systems,the CSI can be acquired using the SRS transmission relying on thechannel reciprocity. For FDD systems, on the other hand, the CSI can beacquired using the CSI-RS transmission from the eNB, and CSI acquisitionand feedback from the UE. In legacy FDD systems, the CSI feedbackframework is ‘implicit’ in the form of CQI/PMI/RI derived from acodebook assuming SU transmission from the eNB. Because of the inherentSU assumption while deriving CSI, this implicit CSI feedback isinadequate for MU transmission. Since future (e.g., NR) systems arelikely to be more MU-centric, this SU-MU CSI mismatch will be abottleneck in achieving high MU performance gains. Another issue withimplicit feedback is the scalability with larger number of antenna portsat the eNB. For large number of antenna ports, the codebook design forimplicit feedback is quite complicated, and the designed codebook is notguaranteed to bring justifiable performance benefits in practicaldeployment scenarios (for example, only a small percentage gain can beshown at the most).

In 5G or NR systems, the above-mentioned CSI reporting paradigm from LTEis also supported and referred to as Type I CSI reporting. In additionto Type I, a high-resolution CSI reporting, referred to as Type II CSIreporting, is also supported to provide more accurate CSI information togNB for use cases such as high-order MU-MIMO.

All the following components and embodiments are applicable for ULtransmission with CP-OFDM (cyclic prefix OFDM) waveform as well asDFT-SOFDM (DFT-spread OFDM) and SC-FDMA (single-carrier FDMA) waveforms.Furthermore, all the following components and embodiments are applicablefor UL transmission when the scheduling unit in time is either onesubframe (which can consist of one or multiple slots) or one slot.

In the present disclosure, the frequency resolution (reportinggranularity) and span (reporting bandwidth) of CSI reporting can bedefined in terms of frequency “subbands” and “CSI reporting band” (CRB),respectively.

A subband for CSI reporting is defined as a set of contiguous PRBs whichrepresents the smallest frequency unit for CSI reporting. The number ofPRBs in a subband can be fixed for a given value of DL system bandwidth,configured either semi-statically via higher-layer/RRC signaling, ordynamically via L1 DL control signaling or MAC control element (MAC CE).The number of PRBs in a subband can be included in CSI reportingsetting.

“CSI reporting band” is defined as a set/collection of subbands, eithercontiguous or non-contiguous, wherein CSI reporting is performed. Forexample, CSI reporting band can include all the subbands within the DLsystem bandwidth. This can also be termed “full-band”. Alternatively,CSI reporting band can include only a collection of subbands within theDL system bandwidth. This can also be termed “partial band”.

The term “CSI reporting band” is used only as an example forrepresenting a function. Other terms such as “CSI reporting subband set”or “CSI reporting bandwidth” can also be used.

FIG. 12 illustrates an example antenna port layout 1200 according toembodiments of the present disclosure. The embodiment of the antennaport layout 1200 illustrated in FIG. 12 is for illustration only. FIG.12 does not limit the scope of this disclosure to any particularimplementation of the antenna port layout 1200.

As illustrated in FIG. 12 , N₁ and N₂ are the number of antenna portswith the same polarization in the first and second dimensions,respectively. For 2D antenna port layouts, N₁>1, N₂>1, and for 1Dantenna port layouts N₁>1 and N₂=1. Therefore, for a dual-polarizedantenna port layout, the total number of antenna ports is 2N₁N₂.

As described in U.S. Pat. No. 10,659,118, issued May 19, 2020 andentitled “Method and Apparatus for Explicit CSI Reporting in AdvancedWireless Communication Systems,” which is incorporated herein byreference in its entirety, a UE is configured with high-resolution(e.g., Type II) CSI reporting in which the linear combination based TypeII CSI reporting framework is extended to include a frequency dimensionin addition to the first and second antenna port dimensions.

FIG. 13 illustrates a 3D grid 1300 of the oversampled DFT beams (1stport dim., 2nd port dim., freq. dim.) in which

-   -   1st dimension is associated with the 1st port dimension,    -   2nd dimension is associated with the 2nd port dimension, and    -   3rd dimension is associated with the frequency dimension.        The basis sets for 1st and 2nd port domain representation are        oversampled DFT codebooks of length-N₁ and length-N₂,        respectively, and with oversampling factors O₁ and O₂,        respectively. Likewise, the basis set for frequency domain        representation (i.e., 3rd dimension) is an oversampled DFT        codebook of length-N₃ and with oversampling factor O₃. In one        example, O₁=O₂=O₃=4. In another example, the oversampling        factors O_(i) belongs to {2, 4, 8}. In yet another example, at        least one of O₁, O₂, and O₃ is higher layer configured (via RRC        signaling).

A UE is configured with higher layer parameter CodebookType set to‘TypeII-Compression’ or ‘TypeIII’ for an enhanced Type II CSI reportingin which the pre-coders for all subbands (SBs) and for a given layerl=1, . . . , v, where v is the associated RI value, is given by either

$\begin{matrix}{{W^{l} = {{AC_{l}B^{H}} = {{{\left\lbrack {a_{0}a_{1}\ldots a_{L - 1}} \right\rbrack\begin{bmatrix}C_{l,0,0} & C_{l,0,1} & \ldots & C_{l,0,{M - 1}} \\C_{l,1,0} & C_{l,1,1} & \ldots & C_{l,1,{M - 1}} \\ \vdots & \vdots & \vdots & \vdots \\C_{l,{L - 1},0} & C_{l,{L - 1},1} & \ldots & C_{l,{L - 1},{M - 1}}\end{bmatrix}}\left\lbrack {b_{0}b_{1}\ldots b_{M - 1}} \right\rbrack}^{H}\text{⁠} = {{{\sum}_{f = 0}^{M - 1}{\sum}_{i = 0}^{L - 1}{c_{l,i,f}\left( {a_{i}b_{f}^{H}} \right)}} = {{\sum}_{i = 0}^{L - 1}{\sum}_{f = 0}^{M - 1}{c_{l,i,f}\left( {a_{i}b_{f}^{H}} \right)}}}}}},} & \left( {{Eq}.1} \right)\end{matrix}$ or $\begin{matrix}{W^{l} = {{\begin{bmatrix}A & 0 \\0 & A\end{bmatrix}\ C_{l}B^{H}} = {\begin{bmatrix}{a_{0}a_{1}\ldots a_{L - 1}} & 0 \\0 & {a_{0}a_{1}\ldots a_{L - 1}}\end{bmatrix}{{\begin{bmatrix}C_{l,0,0} & C_{l,0,1} & \ldots & C_{l,0,{M - 1}} \\C_{l,1,0} & C_{l,1,1} & \ldots & C_{l,1,{M - 1}} \\ \vdots & \vdots & \vdots & \vdots \\C_{l,{L - 1},0} & C_{l,{L - 1},1} & \ldots & C_{l,{L - 1},{M - 1}}\end{bmatrix}{{{\left\lbrack {b_{0}b_{1}\ldots b_{M - 1}} \right\rbrack^{H} = \text{ }\begin{bmatrix}{{\sum}_{f = 0}^{M - 1}{\sum}_{i = 0}^{L - 1}{c_{l,i,f}\left( {a_{i}b_{f}^{H}} \right)}} \\{{\sum}_{f = 0}^{M - 1}{\sum}_{i = 0}^{L - 1}{c_{l,{i + L},f}\left( {a_{i}b_{f}^{H}} \right)}}\end{bmatrix}},}}}}}}} & \left( {{Eq}.2} \right)\end{matrix}$where

-   -   N₁ is a number of antenna ports in a first antenna port        dimension (having the same antenna polarization),    -   N₂ is a number of antenna ports in a second antenna port        dimension (having the same antenna polarization),    -   N₃ is a number of SBs for PMI reporting or number of FD units or        number of FD components (that comprise the CSI reporting band)        or a total number of precoding matrices indicated by the PMI,    -   a_(i) is a 2N₁N₂×1 (Eq. 1) or N₁N₂×1 (Eq. 2) column vector,    -   b_(f) is a N₃×1 column vector,    -   c_(l,i,f) is a complex coefficient.

In a variation, when the UE reports a subset K<2LM coefficients (where Kis either fixed, configured by the gNB or reported by the UE), then thecoefficient c_(l,i,f) in precoder equations Eq. 1 or Eq. 2 is replacedwith x_(l,i,f)×c_(l,i,f), where

-   -   x_(l,i,f)=1 if the coefficient c_(l,i,f) is reported by the UE        according to some embodiments of this invention.    -   x_(l,i,f)=0 otherwise (i.e., c_(l,i,f) is not reported by the        UE).        The indication whether x_(l,i,f)=1 or 0 is according to some        embodiments of this invention. For example, it can be via a        bitmap.

In a variation, the precoder equations Eq. 1 or Eq. 2 are respectivelygeneralized to

$\begin{matrix}{W^{l} = {{{\sum}_{i = 0}^{L - 1}{\sum}_{f = 0}^{M_{i - 1}}} = {c_{l,i,f}\left( {a_{i}b_{i}^{H}} \right)}}} & \left( {{Eq}.3} \right)\end{matrix}$ and $\begin{matrix}{{W^{l} = \begin{bmatrix}{{\sum}_{i = 0}^{L - 1}{\sum}_{f = 0}^{M_{i} - 1}{c_{l,i,f}\left( {a_{i}b_{i,f}^{H}} \right)}} \\{{\sum}_{i = 0}^{L - 1}{\sum}_{= 0}^{M_{i} - 1}{c_{l,{i + L},f}\left( {a_{i}b_{i,f}^{H}} \right)}}\end{bmatrix}},} & \left( {{Eq}.4} \right)\end{matrix}$where for a given i, the number of basis vectors is M_(i) and thecorresponding basis vectors are {b_(i,f)}. Note that M_(i) is the numberof coefficients c_(l,i,f) reported by the UE for a given i, whereM_(i)≤M (where {M_(i)} or ΣM_(i) is either fixed, configured by the gNBor reported by the UE).

The columns of W^(l) are normalized to norm one. For rank R or R layers(v=R), the pre-coding matrix is given by

$W^{(R)} = {{\frac{1}{\sqrt{R}}\left\lbrack {W^{1}\ W^{2}\ \ldots W^{R}} \right\rbrack}.}$Eq. 2 is assumed in the rest of the disclosure. The embodiments of thedisclosure, however, are general and are also application to Eq. 1, Eq.3 and Eq. 4.

Here L≤2N₁N₂ and M≤N₃. If L=2N₁N₂, then A is an identity matrix, andhence not reported. Likewise, if M=N₃, then B is an identity matrix, andhence not reported. Assuming L<2N₁N₂, in an example, to report columnsof A, the oversampled DFT codebook is used. For instance, a_(i)=v_(l,m),where the quantity v_(l,m) is given by

$\begin{matrix}{u_{m} = \left\{ \begin{matrix}\left\lbrack \begin{matrix}1 & e^{j\frac{2\pi m}{O_{2}N_{2}}} & \ldots & e^{{j\frac{2\pi{m({N_{2} - 1})}}{O_{2}N_{2}}}\rbrack}\end{matrix} \right. & {N_{2} > 1} \\1 & {N_{2} = 1}\end{matrix} \right.} \\{v_{l,m} = \left\lbrack {\begin{matrix}u_{m} & {e^{j\frac{2\pi l}{O_{1}N_{1}}}u_{m}} & \ldots & e^{j\frac{2\pi{l({N_{1} - 1})}}{O_{1}N_{1}}}\end{matrix}u_{m}} \right\rbrack^{T}}\end{matrix}.$

Similarly, assuming M<N₃, in an example, to report columns of B, theoversampled DFT codebook is used. For instance, b_(f)=w_(f), where thequantity w_(f) is given by

$w_{f} = {\begin{bmatrix}1 & e^{j\frac{2\pi n_{3,l}^{(f)}}{O_{3}N_{3}}} & e^{j\frac{2{\pi \cdot 2}n_{3,l}^{(f)}}{O_{3}N_{3}}} & \ldots & e^{j\frac{2{\pi \cdot {({N_{3} - 1})}}n_{3,l}^{(f)}}{O_{3}N_{3}}}\end{bmatrix}^{T}.}$

When O₃=1, the FD basis vector for layer l∈{1, . . . , v} (where v isthe RI or rank value) is given byw _(f) =[y _(0,l) ^((f)) y _(1,l) ^((f)) . . . y _(N) ₃ _(−1,l)^((f))]^(T),where

$y_{t,l}^{(f)} = e^{j\frac{2\pi tn_{3,l}^{(f)}}{N_{3}}}$and n_(3,l)=[n_(3,l) ⁽⁰⁾, . . . , n_(3,l) ^((M-1))] where n_(3,l)^((f))∈{0, 1, . . . , N₃−1}.

In another example, discrete cosine transform DCT basis is used toconstruct/report basis B for the 3^(rd) dimension. The m-th column ofthe DCT compression matrix is simply given by

$\left\lbrack W_{f} \right\rbrack_{nm} = \left\{ {\begin{matrix}{\frac{1}{\sqrt{K}},{n = 0}} \\{{\sqrt{\frac{2}{K}}\cos\frac{{\pi\left( {{2m} + 1} \right)}n}{2K}},{n = 1},{{\ldots K} - 1}}\end{matrix},{{{and}K} = N_{3}},{{{and}m} = 0},\ldots,{N_{3} - {1.}}} \right.$

Since DCT is applied to real valued coefficients, the DCT is applied tothe real and imaginary components (of the channel or channeleigenvectors) separately. Alternatively, the DCT is applied to themagnitude and phase components (of the channel or channel eigenvectors)separately. The use of DFT or DCT basis is for illustration purposeonly. The disclosure is applicable to any other basis vectors toconstruct/report A and B.

On a high level, a precoder W^(l) can be described as follows.W=A _(l) C _(l) B _(l) ^(H) =W ₁ {tilde over (W)} ₂ W _(f) ^(H),  (5)where A=W₁ corresponds to the Rel. 15 W₁ in Type II CSI codebook [REF8],and B=W_(f).

The C={tilde over (W)}₂ matrix consists of all the required linearcombination coefficients (e.g., amplitude and phase or real orimaginary). Each reported coefficient (c_(l,i,f)=p_(l,i,f)ϕ_(l,i,f)) in{tilde over (W)}₂ is quantized as amplitude coefficient (p_(l,i,f)) andphase coefficient (ϕ_(l,i,f)). In one example, the amplitude coefficient(p_(l,i,f)) is reported using a A-bit amplitude codebook where A belongsto {2, 3, 4}. If multiple values for A are supported, then one value isconfigured via higher layer signaling. In another example, the amplitudecoefficient (p_(l,i,f)) is reported as p_(l,i,f)=p_(l,i,f) ⁽¹⁾p_(l,i,f)⁽²⁾ where

-   -   p_(l,i,f) ⁽¹⁾ is a reference or first amplitude which is        reported using a A1-bit amplitude codebook where A1 belongs to        {2, 3, 4}, and    -   p_(l,i,f) ⁽²⁾ is a differential or second amplitude which is        reported using a A2-bit amplitude codebook where A2≤A1 belongs        to {2, 3, 4}.

For layer l, let us denote the linear combination (LC) coefficientassociated with spatial domain (SD) basis vector (or beam) i∈{0, 1, . .. , 2L−1} and frequency domain (FD) basis vector (or beam) f∈{0, 1, . .. , M−1} as c_(l,i,f), and the strongest coefficient as c_(l,i*,f*). Thestrongest coefficient is reported out of the K_(NZ) non-zero (NZ)coefficients that is reported using a bitmap, whereK_(NZ)≤K₀=┌β×2LM┐<2LM and β is higher layer configured. The remaining2LM−K_(NZ) coefficients that are not reported by the UE are assumed tobe zero. The following quantization scheme is used to quantize/reportthe K_(NZ) NZ coefficients.

The UE reports the following for the quantization of the NZ coefficientsin {tilde over (W)}₂

-   -   A X-bit indicator for the strongest coefficient index (i*, f*),        where X=┌log₂ K_(NZ)┐ or ┌log₂ 2L┐.        -   Strongest coefficient c_(l,i*,f*)=1 (hence its            amplitude/phase are not reported)    -   Two antenna polarization-specific reference amplitudes is used.        -   For the polarization associated with the strongest            coefficient c_(l,i*,f*)=1, since the reference amplitude            p_(l,i,f) ⁽¹⁾=1, it is not reported        -   For the other polarization, reference amplitude p_(l,i,f)            ⁽¹⁾ is quantized to 4 bits            -   The 4-bit amplitude alphabet is

$\begin{matrix}{\left\{ {1,\left( \frac{1}{2} \right)^{\frac{1}{4}},\left( \frac{1}{4} \right)^{\frac{1}{4}},\left( \frac{1}{8} \right)^{\frac{1}{4}},\ldots,\left( \frac{1}{2^{14}} \right)^{\frac{1}{4}}} \right\}.} & \end{matrix}$

-   -   For {c_(l,i,f), (i, f)≠(i*, f*)}:        -   For each polarization, differential amplitudes p_(l,i,f) ⁽²⁾            of the coefficients calculated relative to the associated            polarization-specific reference amplitude and quantized to 3            bits            -   The 3-bit amplitude alphabet is

$\left\{ {1,\frac{1}{\sqrt{2}},\frac{1}{2},\frac{1}{2\sqrt{2}},\frac{1}{4},\frac{1}{4\sqrt{2}},\frac{1}{8},\frac{1}{8\sqrt{2}}} \right\}.$

-   -   -   -   Note: The final quantized amplitude p_(l,i,f) is given                by p_(l,i,f) ⁽¹⁾×p_(l,i,f) ⁽²⁾

        -   Each phase is quantized to either 8PSK (N_(ph)=8) or 16PSK            (N_(ph)=16) (which is configurable).

For the polarization r*∈{0,1} associated with the strongest coefficientc_(l,i*,f*), we have

$r^{*} = \left\lfloor \frac{i^{*}}{L} \right\rfloor$and the reference amplitude p_(l,i,f) ⁽¹⁾=p_(l,r*) ⁽¹⁾=1. For the otherpolarization r∈{0,1} and r≠r*, we have

$r = {\left( {\left\lfloor \frac{i^{*}}{L} \right\rfloor + 1} \right){mod}2}$and the reference amplitude p_(l,i,f) ⁽¹⁾=p_(l,r) ⁽¹⁾ is quantized(reported) using the 4-bit amplitude codebook mentioned above.

A UE can be configured to report M FD basis vectors. In one example,

${M = \left\lceil {p \times \frac{N_{3}}{R}} \right\rceil},$where R is higher-layer configured from {1,2} and p is higher-layerconfigured from

$\left\{ {\frac{1}{4},\frac{1}{2}} \right\}.$In one example, the p value is higher-layer configured for rank 1-2 CSIreporting. For rank >2 (e.g., rank 3-4), the p value (denoted by v₀) canbe different. In one example, for rank 1-4, (p,v₀) is jointly configuredfrom

$\left\{ {\left( {\frac{1}{2},\frac{1}{4}} \right),\left( {\frac{1}{4},\frac{1}{4}} \right),\left( {\frac{1}{4},\frac{1}{8}} \right)} \right\},$i.e.

$M = \left\lceil {p \times \frac{N_{3}}{R}} \right\rceil$for rank 1-2 and

$M = \left\lceil {v_{0} \times \frac{N_{3}}{R}} \right\rceil$for rank 3-4. In one example, N₃=N_(SB)×R where N_(SB) is the number ofSBs for CQI reporting.

A UE can be configured to report M FD basis vectors in one-step from N₃basis vectors freely (independently) for each layer l∈{0, 1, . . . ,v−1} of a rank v CSI reporting. Alternatively, a UE can be configured toreport M FD basis vectors in two-step as follows.

-   -   In step 1, an intermediate set (InS) comprising N₃′<N₃ basis        vectors is selected/reported, wherein the InS is common for all        layers.    -   In step 2, for each layer l∈{0, 1, . . . , v−1} of a rank v CSI        reporting, M FD basis vectors are selected/reported freely        (independently) from N₃′ basis vectors in the InS.

In one example, one-step method is used when N₃≤19 and two-step methodis used when N₃>19. In one example, M₃′=┌αM┐ where α>1 is either fixed(to 2 for example) or configurable.

The codebook parameters used in the DFT based frequency domaincompression (eq. 5) are (L, p, v₀, β, α, N_(ph)). In one example, theset of values for these codebook parameters are as follows.

-   -   L: the set of values is {2,4} in general, except L∈{2,4,6} for        rank 1-2, 32 CSI-RS antenna ports, and R=1.    -   p for rank 1-2, and (p, v₀) for rank 3-4:

$p \in {\left\{ {\frac{1}{2},\frac{1}{4}} \right\}{and}\left( {p,v_{0}} \right)} \in {\left\{ {\left( {\frac{1}{2},\frac{1}{4}} \right),\left( {\frac{1}{4},\frac{1}{4}} \right),\left( {\frac{1}{4},\frac{1}{8}} \right)} \right\}.}$

$\beta \in {\left\{ {\frac{1}{4},\frac{1}{2},\frac{3}{4}} \right\}.}$

-   -   α∈{1.5,2,2.5,3}    -   N_(ph) ∈{8,16}.

In another example, the set of values for the codebook parameters (L, p,v₀, β, α, N_(ph)) are as follows: α=2, N_(ph)=16, and

L p = y₀ (RI = 1-2) p = v₀ (RI = 3-4) β Restriction (if any) 2 ¼ ⅛ ¼ 2 ¼⅛ ½ 4 ¼ ⅛ ¼ 4 ¼ ⅛ ½ 4 ½ ¼ ½ 6 ¼ — ½ RI = 1-2, 32 ports 4 ¼ ¼ ¾ 6 ¼ — ¾RI = 1-2, 32 ports

The above-mentioned framework (equation 5) represents theprecoding-matrices for multiple (N₃) FD units using a linear combination(double sum) over 2L SD beams and M FD beams. This framework can also beused to represent the precoding-matrices in time domain (TD) byreplacing the FD basis matrix W_(f) with a TD basis matrix W_(t),wherein the columns of W_(t) comprises M TD beams that represent someform of delays or channel tap locations. Hence, a precoder W^(l) can bedescribed as follows.W=A _(l) C _(l) B _(l) ^(H) =W ₁ {tilde over (W)} ₂ W _(t) ^(H),  (5A)

In one example, the M TD beams (representing delays or channel taplocations) are selected from a set of N₃ TD beams, i.e., N₃ correspondsto the maximum number of TD units, where each TD unit corresponds to adelay or channel tap location. In one example, a TD beam corresponds toa single delay or channel tap location. In another example, a TD beamcorresponds to multiple delays or channel tap locations. In anotherexample, a TD beam corresponds to a combination of multiple delays orchannel tap locations.

The rest of the disclosure is applicable to both space-frequency(equation 5) and space-time (equation 5A) frameworks.

In general, for layer l=0, 1, . . . , v−1, where v is the rank valuereported via RI, the pre-coder (cf. equation 5 and equation 5A) includesthe codebook components summarized in Table 1.

TABLE 1 Codebook Components Index Components Description 0 L_(l) numberof SD beams 1 M_(l) number of FD/TD beams 2 {a_(l,i)}_(i=0) ^(L) ^(l) ⁻¹set of SD beams comprising columns of A_(l) 3 {b_(l,f)}_(f=0) ^(M) ^(l)⁻¹ set of FD/TD beams comprising columns of B_(l) 4 {x_(l,i,f)} bitmapindicating the indices of the non-zero (NZ) coefficients 5 {p_(l,i,f)}amplitudes of NZ coefficients indicated via the bitmap 6 {ϕ_(l,i,f)}phases of NZ coefficients indicated via the bitmap

In one example, the number of SD beams is layer-common, i.e., L_(l)=Lfor all l values. In one example, the set of SD basis is layer-common,i.e., a_(l,i)=a_(i) for all l values. In one example, the number ofFD/TD beams is layer-pair-common or layer-pair-independent, i.e.,M₀=M₁=M for layer pair (0, 1), M₂=M₃=M′ for layer pair (2, 3), and M andM′ can have different values. In one example, the set of FD/TD basis islayer-independent, i.e., {b_(l,f)} can be different for different lvalues. In one example, the bitmap is layer-independent, i.e.,{β_(l,i,f)} can be different for different l values. In one example, theSCI is layer-independent, i.e., {SCI_(l)} can be different for differentl values. In one example, the amplitudes and phases arelayer-independent, i.e., {p_(l,i,f)} and {ϕ_(l,i,f)} can be differentfor different l values.

In one example, when the SD basis W₁ is a port selection, then thecandidate values for L or L_(l) include 1, and the candidate values forthe number of CSI-RS ports N_(CSI-RS) include 2.

In embodiment A, for SD basis, the set of SD beams {a_(l,i)}_(i=0) ^(L)^(l) ⁻¹ comprising columns of A_(l) is according to at least one of thefollowing alternatives. The SD basis is common for the two antennapolarizations, i.e., one SD basis is used for both antennapolarizations.

In one alternative Alt A-1, the SD basis is analogous to the W₁component in Rel.15 Type II port selection codebook, wherein the L_(l)antenna ports or column vectors of A_(l) are selected by the index

$q_{1} \in \left\{ {0,1,\ldots,{\left\lceil \frac{P_{{CSI}‐{RS}}}{2d} \right\rceil - 1}} \right\}$(this requires

$\left\lceil {\log_{2}\left\lceil \frac{P_{{CSI}‐{RS}}}{2d} \right\rceil} \right\rceil$bits), where

$d \leq {{\min\left( {\frac{P_{{CSI}‐{RS}}}{2},L_{l}} \right)}.}$In one example, d∈{1,2,3,4}. To select columns of A_(l), the portselection vectors are used. For instance, a_(i)=v_(m), where thequantity v_(m) is a P_(CSI-RS)/2-element column vector containing avalue of 1 in element (mmod P_(CSI-RS)/2) and zeros elsewhere (where thefirst element is element 0). The port selection matrix is then given by

$W_{1} = {A_{l} = {{\begin{bmatrix}X & 0 \\0 & X\end{bmatrix}{where}X} = \left\lbrack {\begin{matrix}v_{q_{1}d} & v_{{q_{1}d} + 1} & \ldots & \left. v_{{q_{1}d} + L_{l} - 1} \right\rbrack\end{matrix}.} \right.}}$

In one alternative Alt A-2, the SD basis selects L_(l) antenna portsfreely, i.e., the L_(l) antenna ports per polarization or column vectorsof A_(l) are selected freely by the index

$q_{1} \in \left\{ {0,1,\ldots\ ,{\begin{pmatrix}\frac{P_{{CSI}‐{RS}}}{2} \\L_{l}\end{pmatrix} - 1}} \right\}$(this requires

$\left\lceil {\log_{2}\begin{pmatrix}\frac{P_{{CSI}‐{RS}}}{2} \\L_{l}\end{pmatrix}} \right\rceil$bits). To select columns of A_(l), the port selection vectors are used.For instance, a_(i)=v_(m), where the quantity v_(m) is aP_(CMI-RS)/2-element column vector containing a value of 1 in element (mmod P_(CSI-RS)/2) and zeros elsewhere (where the first element iselement 0). Let {x₀, x₁, . . . , x_(L) _(l) ⁻¹} be indices of selectionvectors selected by the index q₁. The port selection matrix is thengiven by

$W_{1} = {A_{l} = \begin{bmatrix}X & 0 \\0 & X\end{bmatrix}}$where

$X = {\begin{bmatrix}v_{x_{0}} & v_{x_{1}} & \ldots & v_{x_{L_{l} - 1}}\end{bmatrix}.}$

In one alternative Alt A-3, the SD basis selects L_(l) DFT beams from anoversampled DFT codebook, i.e., a_(i)=v_(i) ₁ _(,i) ₂ , where thequantity v_(i) ₁ _(,i) ₂ is given by

$\begin{matrix}{u_{i_{2}} = \left\{ \begin{matrix}\begin{bmatrix}1 & e^{j\frac{2\pi m}{O_{2}N_{2}}} & \ldots & e^{j\frac{2\pi{m({N_{2} - 1})}}{O_{2}N_{2}}}\end{bmatrix} & {N_{2} > 1} \\1 & {N_{2} = 1}\end{matrix} \right.} \\{v_{i_{1},i_{2}} = \left\lbrack \begin{matrix}u_{i_{2}} & {e^{j\frac{2\pi i_{1}}{O_{1}N_{1}}}u_{i_{2}}} & \ldots & {e^{j\frac{2\pi{i_{1}({N_{1} - 1})}}{O_{1}N_{1}}}u_{i_{2}}}\end{matrix}\text{  } \right\rbrack^{T}}\end{matrix}.$

In one example, this selection of L_(l) DFT beams is from a set oforthogonal DFT beams comprising N₁N₂ two-dimensional DFT beams.

In one alternative Alt A-4, the SD basis is fixed (hence, not selectedby the UE). For example, the SD basis includes all

$L_{l} = \frac{K_{SD}}{2}$SD antenna ports for each antenna polarization (for a dual-polarizedantenna port layout at the gNB). Or, the SD basis includes allL_(l)=K_(SD) SD antenna ports (for a co-polarized antenna port layout atthe gNB). In one example, K_(SD)=2N₁N₂. In another example,K_(SD)<2N₁N₂. In one example, the UE can be configured with K_(SD)=2N₁N₂or K_(SD)<2N₁N₂. In one example, K_(SD)−S where S is fixed, e.g., {4,8}.Note that K_(SD) is a number of CSI-RS ports in SD.

In embodiment AA, a variation of embodiment A, the SD basis is selectedindependently for each of the two antenna polarizations, according to atleast one of Alt A-1 through Alt A-4.

In embodiment B, for FD/TD basis, the set of FD/TD beams {b_(l,f)}_(f=0)^(M) ^(l) ⁻¹ comprising columns of B_(l) is according to at least one ofthe following alternatives.

In one alternative Alt B-1, the FD/TD basis selection to similar to AltA-1, i.e., the M_(l) FD/TD units ports or column vectors of B_(l) areselected by the index

$q_{2} \in \left\{ {0,1,\ldots,{\left\lceil \frac{N_{3}}{e} \right\rceil - 1}} \right\}$(this requires

$\left\lceil {\log_{2}\left\lceil \frac{N_{3}}{e} \right\rceil} \right\rceil$bits), where e≤min(N₃,M_(l)). In one example, e∈{1,2,3,4}. To selectcolumns of B_(l), the selection vectors are used. For instance,b_(f)=v_(z), where the quantity v_(z) is a N₃-element column vectorcontaining a value of 1 in element (z mod N₃) and zeros elsewhere (wherethe first element is element 0). The selection matrix is then given byW _(f) =B _(l) =[V _(q) ₂ _(e) v _(q) ₂ _(e+1) . . . v _(q) ₂ _(e+M)_(l) ⁻¹].

In one alternative Alt B-2, the FD/TD basis selects M_(l) FD/TD unitsfreely, i.e., the M_(l) FD/TD units or column vectors of B_(l) areselected freely by the index

$q_{2} \in \left\{ {0,1,\ldots,{\begin{pmatrix}N_{3} \\M_{l}\end{pmatrix} - 1}} \right\}$(this requires

$\left\lceil {\log_{2}\begin{pmatrix}N_{3} \\M_{l}\end{pmatrix}} \right\rceil$bits). To select columns of B_(l), the selection vectors are used. Forinstance, b_(f)=v_(z), where the quantity v_(z) is a N₃-element columnvector containing a value of 1 in element (z mod N₃) and zeros elsewhere(where the first element is element 0). Let {x₀, x₁, . . . , x_(M) _(l)⁻¹} be indices of selection vectors selected by the index q₂. Theselection matrix is then given by

$W_{f} = {B_{l} = {\begin{bmatrix}v_{x_{0}} & v_{x_{1}} & \ldots & v_{x_{M_{l} - 1}}\end{bmatrix}.}}$

In one alternative Alt B-3, the FD/TD basis selects M_(l) DFT beams froman oversampled DFT codebook, i.e., b_(f)=w_(f), where the quantity w_(f)is given by

$w_{f} = \left\lbrack {\begin{matrix}1 & e^{j\frac{2\pi f}{O_{3}N_{3}}} & \ldots & \left. e^{j\frac{2\pi{f({N_{3} - 1})}}{O_{3}N_{3}}} \right\rbrack\end{matrix}.} \right.$

In one example, this selection of M_(l) DFT beams is from a set oforthogonal DFT beams comprising N₃ DFT beams. In one example, O₃=1.

In one alternative Alt B-4, the FD/TD basis is fixed (hence, notselected by the UE). For example, the FD/TD basis includes allM_(l)=K_(FD) FD antenna ports. In one example, K_(FD)=N₃. In anotherexample, K_(FD)<N₃. In one example, the UE can be configured withK_(FD)=N₃ or K_(FD)<N₃. In one example, K_(FD) ∈S where S is fixed. Notethat K_(FD) is a number of CSI-RS ports in FD.

In one example, K_(SD)×K_(FD)=P_(CSIRS) is a total number of(beam-formed) CSI-RS ports.

In embodiment C, the SD and FD/TD bases are according to at least one ofthe alternatives in Table 2.

TABLE 2 alternatives for SD and FD/TD bases Alt SD basis FD/TD basis C-0Alt A-1 Alt B-1 C-1 Alt B-2 C-2 Alt B-3 C-3 Alt B-4 C-4 Alt A-2 Alt B-1C-5 Alt B-2 C-6 Alt B-3 C-7 Alt B-4 C-8 Alt A-3 Alt B-1 C-9 Alt B-2 C-10Alt B-3 C-11 Alt B-4

As defined above, N₃ is a number of FD units for PMI reporting and thePMI indicates N₃ precoding matrices, one for each FD unit. An FD unitcan also be referred to as a PMI subband. Let t∈{0, 1, . . . , N₃−1} bean index to indicate an FD unit. Note that PMI subband can be differentfrom CQI subband.

Let a parameter R indicate a number of PMI subbands in each CQI subband.As explained in Section 5.2.2.2.5 of [REF8], this parameter controls thetotal number of precoding matrices N₃ indicated by the PMI as a functionof the number of subbands in csi-ReportingBand (configured to the UE forCSI reporting), the subband size (N_(PRB) ^(SB)) configured by thehigher-level parameter subbandSize and of the total number of PRBs inthe bandwidth part according to Table 5.2.1.4-2 [REF8], as follows:

-   -   When R=1: One precoding matrix is indicated by the PMI for each        subband in csi-ReportingBand.    -   When R=2:        -   For each subband in csi-ReportingBand that is not the first            or last subband of a band-width part (BWP), two precoding            matrices are indicated by the PMI: the first precoding            matrix corresponds to the first N_(PRB) ^(SB)/2 PRBs of the            subband and the second precoding matrix corresponds to the            last N_(PRB) ^(SB)/2 PRBs of the subband.        -   For each subband in csi-ReportingBand that is the first or            last subband of a BWP            -   If

${\left( {N_{{BWP},i}^{start}{mod}\ N_{PRB}^{SB}} \right) \geq \frac{N_{PRB}^{SB}}{2}},$

-   -   -   -    one precoding matrix is indicated by the PMI                corresponding to the first subband. If

${\left( {N_{{BWP},i}^{start}{mod}\ N_{PRB}^{SB}} \right) < \frac{N_{PRB}^{SB}}{2}},$

-   -   -   -    two precoding matrices are indicated by the PMI                corresponding to the first subband: the first precoding                matrix corresponds to the first

$\frac{N_{PRB}^{SB}}{2} - \left( {N_{{BWP},i}^{start}{mod}\ N_{PRB}^{SB}} \right)$

-   -   -   -    PRBs of the first subband and the second precoding                matrix corresponds to the last

$\frac{N_{PRB}^{SB}}{2}$

-   -   -   -    PRBs of the first subband.            -   If

${{\left( {N_{{BWP},i}^{start} + N_{{BWP},i}^{size}} \right){mod}N_{PRB}^{SB}} \leq \frac{N_{PRB}^{SB}}{2}},$

-   -   -   -    one precoding matrix is indicated by the PMI                corresponding to the last subband. If

${{\left( {N_{{BWP},i}^{start} + N_{{BWP},i}^{size}} \right){mod}N_{PRB}^{SB}} > \frac{N_{PRB}^{SB}}{2}},$

-   -   -   -    two precoding matrices are indicated by the PMI                corresponding to the last subband: the first precoding                matrix corresponds to the first

$\frac{N_{PRB}^{SB}}{2}$

-   -   -   -    PRBs of the last subband and the second precoding                matrix corresponds to the last

${\left( {N_{{BWP},i}^{start} + N_{{BWP},i}^{size}} \right){mod}N_{PRB}^{SB}} - \frac{N_{PRB}^{SB}}{2}$

-   -   -   -    PRBs of the last subband.

    -   When R=N_(PRB) ^(SB): One precoding matrix is indicated by the        PMI for each PRB in csi-ReportingBand.

Here, N_(BWP,i) ^(start) and N_(BWP,i) ^(size) are a starting PRB indexand a total number of PRBs in the BWP i.

In one example, R is fixed, e.g., R=2 or R=N_(PRB) ^(SB). In oneexample, R is configured, e.g., from {1,2} or {1, 2, N_(PRB) ^(SB)} or{2, N_(PRB) ^(SB)}. When R is configured, it is configured via ahigher-layer parameter, e.g., numberOfPMlSubbandsPerCQISubband.

Let P_(CSIRS,SD) and P_(CSIRS,FD) be a number of CSI-RS ports in SD andFD, respectively. The total number of CSI-RS ports isP_(CSIRS,SD)×P_(CSIRS,FD)=P_(CSIRS). Each CSI-RS port can bebeam-formed/pre-coded using a pre-coding/beam-forming vector in SD or FDor both SD and FD. The pre-coding/beam-forming vector for each CSI-RSport can be derived based on UL channel estimation via SRS, assuming(partial) reciprocity between DL and UL channels. Since CSI-RS ports canbe beam-formed in SD as well as FD, the Rel. 15/16 Type II portselection codebook can be extended to perform port selection in both SDand FD followed by linear combination of the selected ports. In the restof the disclosure, some details pertaining to the CSI-RS configuration(beamforming, port numbering, number of CSIRS resources etc.) for thisextension are provided.

In embodiment 1, a UE is configured with higher layer parametercodebookType set to ‘ typeII-PortSelection-r17’ for CSI reporting basedon a new (Rel. 17) Type II port selection codebook in which the portselection (which is in SD) in Rel. 15/16 Type II port selection codebookis extended to FD in addition to SD. The UE is also configured withP_(CSIRS) CSI-RS ports (either in one CSI-RS resource or distributedacross more than one CSI-RS resources) linked with the CSI reportingbased on this new Type II port selection codebook. In one example,P_(CSIRS)=Q. In another example, P_(CSIRS)≥Q. In another example,P_(CSIRS)≤Q. Here, Q=P_(CSIRS,SD)×P_(CSIRS,FD). The UE measuresP_(CSIRS) (or at least Q) beam formed CSI-RS ports, estimates(beam-formed) DL channel, and determines a precoding matrix for each FDunit t∈{0, 1, . . . , N₃−1}.

The value of (P_(CSIRS,SD)/P_(CSIRS,FD)) is determined according to atleast one of the following examples. In one example, (P_(CSIRS,SD),P_(CSIRS,FD))=(2L, M). In one example, (P_(CSIRS,SD)/P_(CSIRS,FD))=(2L,N₃). In one example, (P_(CSIRS,SD), P_(CSIRS,FD))=(U, N₃) where U>2L. Inone example, (P_(CSIRS,SD), P_(CSIRS,FD))=(U, N₃) where U>2L. In oneexample, (P_(CSIRS,SD), P_(CSIRS,FD))=(2L, V) where N₃>V>M. In oneexample, (P_(CSIRS,SD), P_(CSIRS,FD))=(U, V) where U>2L and N₃>V>M.

Note that Q is a number of (SD only or SD-FD) beamforming basis vectorsor bases conveyed via P_(CSIRS) CSI-RS ports. When P_(CSI-RS)=Q, thereis one-to-one mapping between the beamforming bases and CSI-RS ports,i.e., each CSI-RS port is beam-formed using one beamforming basisvector. When Q≥P_(CSIRS), a CSI-RS port conveys more than onebeamforming basis vector, i.e., each CSI-RS port is beam-formed usingmore than one beamforming basis vectors. For example, whenP_(CSIRS,SD)=P_(CSIRS) and P_(CSIRS,FD)=O_(f), thenQ=P_(CSIRS,SD)×P_(CSIRS,FD)=O_(f)P_(CSIRS), and each CSI-RS port conveysO_(f) beamforming basis vectors, and hence is beam-formed using O_(f)beamforming basis vectors. In one example, O_(f) is fixed, e.g.,O_(f)=2. In one example, O_(f) is configured from a set of supportedvalues, e.g., {1,2} or {1,2,4} or {1,2,3} or {1,M}. In one example, theset of supported values is reported by the UE as part of the UEcapability reporting. In one example, O_(f)=1 is mandatory for all UEssupporting the proposed codebook in embodiment 1. The support of anyadditional value (e.g., O_(f)=2) or multiple values is subject to aseparate UE capability signaling.

The value of (P_(CSIRS), O_(f)) is determined according to at least oneof the following examples. In one example, (P_(CSIRS), O_(f))=(2L, M).In one example, (P_(CSIRS), O_(f))=(2L, N₃). In one example, (P_(CSIRS),O_(f))=(U, M) where U>2L. In one example, (P_(CSIRS), O_(f))=(U, N₃)where U>2L. In one example, (P_(CSIRS), O_(f))=(2L, V) where N₃>V>M. Inone example, (P_(CSIRS), O_(f))=(U, V) where U>2L and N₃>V>M.

In these examples, L, M, and N₃ are determined/configured (as explainedabove), and one or both of U and V are either fixed or configured. Theparameters U and V determines intermediate sets of SD and FD ports,respectively. If U>2L, the UE performs SD port selection (2L out of U orL out of

$\left. \frac{U}{2} \right)$using the intermediate set of SD ports and reports the selected SD ports(as part of the CSI report). Likewise, if V>M, UE performs FD portselection (M out of V) using the intermediate set of FD ports andreports the selected FD ports (as part of the CSI report).

In one example, the first

$\frac{P_{CSIRS}}{2}$antenna ports,

$x,{x + 1},\ldots,{x + \frac{P_{CSIRS}}{2} - 1},$corresponds to the first antenna polarization and the last

$\frac{P_{CSIRS}}{2}$antenna ports.

${x + \frac{P_{CSIRS}}{2}},{x + \frac{P_{CSIRS}}{2} + 1},\ldots,{x + P_{CSIRS} - 1},$corresponds to the second antenna polarization. In one example, x=3000.

Assuming Q=P_(CSIRS,SD)×P_(CSIRS,FD) or P_(CSIRS)×O_(f), apre-coding/beam-forming vector to obtain a pre-coder/beam-formed CSI-RSport can be determined as follows.

-   -   Let q=[q₀ q₁ . . . q_(N-1)] be a N×1 pre-coding/beam-forming        vector for SD, where N is a number of antennae used to obtain a        beam-formed/pre-coded CSI-RS port in SD. In one example, q=v_(m)        ₁ _((i)) _(,m) ₂ _((i)) , where i∈{0, 1, . . . , N₁N₂−1} is a        DFT vector corresponding to a two-dimensional antenna layout        with N₁ and N₂ antennae in first and second dimensions,        respectively [(cf. 5.2.2.2.3, REFS]. In one example, q is an        eigenvector of the UL channel (in SD by averaging over FD)        estimated by the gNB using SRS. Note that: q is determined by        gNB (hence, it is unknown or transparent to the UE).    -   Let r=[r₀ r₁ . . . r_(N) ₃ ⁻¹] be a N₃×1 pre-coding/beam-forming        vector for FD. In one example, r_(t)=y_(t,l) ^((f)), hence,        r=[y_(0,l) ^((f)) y_(1,l) ^((f)) . . . y_(N) ₃ _(−1,l) ^((f))],        where f∈{0, 1, . . . , N₃−1} is a DFT vector. In one example, r        is an eigenvector of the UL channel (in FD by averaging over SD)        estimated by the gNB using SRS. Note that: r is determined by        gNB (hence, it is unknown or transparent to the UE).    -   In FD unit t={0, 1, . . . , N₃−1}, a pre-coding/beam-forming        vector is then given by s=q×r_(t). Note that s is common (the        same) for both antenna polarizations. In one example, s=w_(t,l)        ^((i,f))=v_(m) ₁ _((i)) _(,m) ₂ _((i)) ×y_(t,l) ^((f)). Note        that from one FD unit to another, the beam-forming/pre-coding        vector for a given port changes since r_(t) changes.

The numbering (or mapping) of a CSI-RS port x+j, where j∈{0, 1, . . . ,P_(CSIRS)−1} and x=3000, to (SD, FD) port pair (i, f), where i∈{0, 1, .. . , P_(CSIRS,SD)−1} and f∈{0, 1, . . . , P_(CSIRS,FD)−1}, or to theSD-FD beam-forming vector indices (i,f) where i∈{0, 1, . . . ,P_(CSIRS)−1} and f∈{0, 1, . . . , O_(f)−1} is according to at least oneof the following alternatives (Alt). The UE uses the port numbering todetermine a 2L×M coefficient matrix {tilde over (W)}₂ (cf. equation5/5A).

In one alternative Alt 1.1, assuming all P_(CSIRS) CSI-RS ports can bemeasured within each PRB of the configured BWP for CSI-RS measurement,the mapping of CSI-RS port j to the index pair (i, f) is the followingorder SD→FD, i.e., first in SD then in FD. One example is given by thefollowing.

-   -   For the first antenna polarization

$\left( {j \in \left\{ {0,1,\ldots,{\frac{P_{CSIRS}}{2} - 1}} \right\}} \right),$

-   -    ports

${j = 0},1,\ldots,{\frac{P_{{CSIRS},{SD}}}{2} - 1}$

-   -    map to

${i = 0},1,\ldots,{\frac{P_{{CSIRS},{SD}}}{2} - 1}$

-   -    and f=0, ports

${j = \frac{P_{{CSIRS},{SD}}}{2}},{\frac{P_{{CSIRS},{SD}}}{2} + 1},\ldots,{P_{{CSIRS},{SD}} - 1}$

-   -    map to

${i = 0},1,\ldots,{\frac{P_{{CSIRS},{SD}}}{2} - 1}$

-   -    and f=1, and so on. Mathematically, this is equivalent to

$i = {{j{mod}\frac{P_{{CSIRS},{SD}}}{2}{and}f} = {\left\lfloor \frac{2j}{P_{{CSIRS},{SD}}} \right\rfloor = {\frac{2\left( {j - i} \right)}{P_{{CSIRS},{SD}}}.}}}$

-   -   For the second antenna polarization

$\left( {j \in \left\{ {\frac{P_{CSIRS}}{2},{\frac{P_{CSIRS}}{2} + 1},\ldots,{P_{CSIRS} - 1}} \right\}} \right),$

-   -    ports

${j = \frac{P_{CSIRS}}{2}},{\frac{P_{CSIRS}}{2} + 1},\ldots,{\frac{P_{CSIRS}}{2} + \frac{P_{{CSIRS},{SD}}}{2} - 1}$

-   -    map to

${i = \frac{P_{{CSIRS},{SD}}}{2}},{\frac{P_{{CSIRS},{SD}}}{2} + 1},\ldots,{P_{{CSIRS},{SD}} - 1}$

-   -    and f=0, ports

${j = {\frac{P_{CSIRS}}{2} + \frac{P_{{CSIRS},{SD}}}{2}}},{\frac{P_{CSIRS}}{2} + \frac{P_{{CSIRS},{SD}}}{2} + 1},\ldots,{\frac{P_{CSIRS}}{2} + P_{{CSIRS},{SD}} - 1}$

-   -    map to

${i = \frac{P_{{CSIRS},{SD}}}{2}},{\frac{P_{{CSIRS},{SD}}}{2} + 1},\ldots,{P_{{CSIRS},{SD}} - 1}$

-   -   and f=1, and so on. Mathematically, this is equivalent to

$i = {{\frac{P_{{CSIRS},{SD}}}{2} + {\left( {j - \frac{P_{CSIRS}}{2}} \right){mod}\frac{P_{{CSIRS},{SD}}}{2}{and}f}} = {\left\lfloor \frac{2\left( {j - \frac{P_{CSIRS}}{2}} \right)}{P_{{CSIRS},{SD}}} \right\rfloor = {\frac{2\left( {\left( {j - \frac{P_{CSIRS}}{2}} \right) - \left( {i - \frac{P_{{CSIRS},{SD}}}{2}} \right)} \right)}{P_{{CSIRS},{SD}}}.}}}$

Likewise, for the case when the mapping is between CSI-RS ports and theSD-FD beam-forming vector indices (i, f), where i∈{0, 1, . . . ,P_(CSIRS)−1} and f∈{0, 1, . . . , O_(f)−1}, the mapping of CSI-RS port jto the index pair (i, f) is the same as in Alt 1.1 except that thenotation P_(CSIRS,SD) and P_(CSIRS,FD) are replaced with P_(CSIRS) andO_(f), respectively.

In one alternative Alt 1.1a, assuming all P_(CSIRS) CSI-RS ports can bemeasured within each PRB of the configured BWP for CSI-RS measurement,the mapping of CSI-RS port j to the index pair (i, f) is the followingorder SD→FD, i.e., first in SD then in FD. One example is given by thefollowing.

-   -   Ports j=0, 1, . . . , P_(CSIRS,SD)−1 map to i=0, 1, . . . ,        P_(CSIRS,SD)−1 and f=0, ports j=P_(CSIRS,SD), P_(CSIRS,SD)+1, .        . . , 2P_(CSIRS,SD)−1 map to i=0, 1, . . . , P_(CSIRS,SD)−1 and        f=1, and so on. Mathematically, this is equivalent to i=j mod        P_(CSIRS,SD) and

$f = {\left\lfloor \frac{j}{P_{{CSIRS},{SD}}} \right\rfloor = {\frac{j - i}{P_{{CSIRS},{SD}}}.}}$

Likewise, for the case when the mapping is between CSI-RS ports and theSD-FD beam-forming vector indices (i, f), where i∈{0, 1, . . . ,P_(CSIRS)−1} and f∈{0, 1, . . . , O_(f)−1}, the mapping of CSI-RS port jto the index pair (i, f) is the same as in Alt 1.1a except that thenotation P_(CSIRS,SD) and P_(CSIRS,FD) are replaced with P_(CSIRS) andO_(f), respectively.

In one alternative Alt 1.2, assuming all P_(CSIRS) CSI-RS ports can bemeasured within each PRB of the configured BWP for CSI-RS measurement,the mapping of CSI-RS port j to the index pair (i, f) is the followingorder FD→SD, i.e., first in FD then in SD. One example is given by thefollowing.

-   -   For the first antenna polarization

$\left( {j \in \left\{ {0,1,\ldots,{\frac{P_{CSIRS}}{2} - 1}} \right\}} \right),$

-   -    ports j=0, 1, . . . , P_(CSIRS,FD)−1 map to i=0 and f=0, 1, . .        . , P_(CSIRS,FD)−1, ports j=P_(CSIRS,FD), P_(CSIRS,FD)+1, . . .        , 2P_(CSIRS,FD)−1 map to i=1 and f=0, 1, . . . , P_(CSIRS,FD)−1,        and so on. Mathematically, this is equivalent to f=j mod        P_(CSIRS,FD) and

$i = {\left\lfloor \frac{j}{P_{{CSIRS},{FD}}} \right\rfloor = {\frac{j - f}{P_{{CSIRS},{FD}}}.}}$

-   -   For the second antenna polarization

$\left( {j \in \left\{ {\frac{P_{CSIRS}}{2},{\frac{P_{CSIRS}}{2} + 1},\ldots,{P_{CSIRS} - 1}} \right\}} \right),$

-   -    ports

${j = \frac{P_{CSIRS}}{2}},{\frac{P_{CSIRS}}{2} + 1},\ldots,{\frac{P_{CSIRS}}{2} + P_{{CSIRS},{FD}} - 1}$

-   -    map to

$i = \frac{P_{{CSIRS},{SD}}}{2}$

-   -    and f=0, 1, . . . , P_(CSIRS,FD)−1, ports

${j = {\frac{P_{CSIRS}}{2} + P_{{CSIRS},{FD}}}},{\frac{P_{CSIRS}}{2} + P_{{CSIRS},{FD}} + 1},\ldots,{\frac{P_{CSIRS}}{2} + {2P_{{CSIRS},{FD}}} - 1}$

-   -    map to

$i = {\frac{P_{{CSIRS},{SD}}}{2} + 1}$

-   -    and f=0, 1, . . . , P_(CSIRS,FD)−1, and so on. Mathematically,        this is equivalent to

$f = {{\left( {j - \frac{P_{CSIRS}}{2}} \right){mod}P_{{CSIRS},{FD}}{and}i} = {{\frac{P_{{CSIRS},{SD}}}{2} + \left\lfloor \frac{j - \frac{P_{CSIRS}}{2}}{P_{{CSIRS},{FD}}} \right\rfloor} = {\frac{P_{{CSIRS},{SD}}}{2} + {\frac{\left( {j - \frac{P_{CSIRS}}{2}} \right) - f}{P_{{CSIRS},{FD}}}.}}}}$

Likewise, for the case when the mapping is between CSI-RS ports and theSD-FD beam-forming vector indices (i, f), where i∈{0, 1, . . . ,P_(CSIRS)−1} and f∈{0, 1, . . . , O_(f)−1}, the mapping of CSI-RS port jto the index pair (i, f) is the same as in Alt 1.2 except that thenotation P_(CSIRS,SD) and P_(CSIRS,FD) are replaced with P_(CSIRS) andO_(f), respectively.

In one alternative Alt 1.2a, assuming all P_(CSIRS) CSI-RS ports can bemeasured within each PRB of the configured BWP for CSI-RS measurement,the mapping of CSI-RS port j to the index pair (i, f) is the followingorder FD→SD, i.e., first in FD then in SD. One example is given by thefollowing.

-   -   Ports j=0, 1, . . . , P_(CSIRS,FD)−1 map to i=0 and f=0, 1, . .        . , P_(CSIRS,FD)−1, ports j=P_(CSIRS,FD), P_(CSIRS,FD)+1, . . .        , 2P_(CSIRS,FD)−1 map to i=1 and f=0, 1, . . . , P_(CSIRS,FD)−1,        and so on. Mathematically, this is equivalent to f=j mod        P_(CSIRS,FD) and

$i = {\left\lfloor \frac{j}{P_{{CSIRS},{FD}}} \right\rfloor = {\frac{j - f}{P_{{CSIRS},{FD}}}.}}$

Likewise, for the case when the mapping is between CSI-RS ports and theSD-FD beam-forming vector indices (i, f), where i∈{0, 1, . . . ,P_(CSIRS)−1} and f∈{0, 1, . . . , O_(f)−1}, the mapping of CSI-RS port jto the index pair (i, f) is the same as in Alt 1.2a except that thenotation P_(CSIRS,SD) and P_(CSIRS,FD) are replaced with P_(CSIRS) andO_(f), respectively.

FIG. 14 illustrates an example mapping of CSI-RS ports to index pairs1400 according to embodiments of the present disclosure. The embodimentof the mapping of CSI-RS ports to index pairs 1400 illustrated in FIG.14 is for illustration only. FIG. 14 does not limit the scope of thisdisclosure to any particular implementation of the mapping of CSI-RSports to index pairs 1400.

In one alternative Alt 1.3, it is assumed that all P_(CSIRS) CSI-RSports can be measured across multiple PRBs (not within each PRB as inAlt 1.1/1.1a/1.2/1.2a), but the multiple PRBs are within each FD unit ofthe configured BWP for CSI-RS measurement. The mapping of CSI-RS port jto the index pair (i, f) is the following order SD→FD, i.e., first in SDthen in FD across multiple PRBs. One of the following examples is usedas illustrated in FIG. 14 ,

-   -   In one example Ex 1.3.1, ports j=0, 1, . . . , P_(CSIRS,SD)−1 in        the first PRB (index g=0) map to i=0, 1, . . . , P_(CSIRS,SD)−1        and f=0, ports j=0, 1, . . . , P_(CSIRS,SD)−1 in the second PRB        (index g=1) map to i=0, 1, . . . , P_(CSIRS,SD)−1 and f=1, and        so on. Mathematically, this is equivalent to i=j and f=g. This        example requires that the number of PRBs in a FD unit equals M.    -   In one example Ex 1.3.2, it is assumed that the number of PRBs        in a FD unit exceeds (or is greater than) M. The number of PRBs        in a FD unit is partitioned into M segments where each segment        comprises one or more than consecutive PRBs. The ports j=0, 1, .        . . , P_(CSIRS,SD)−1 in all PRBs of the first segment (index        s=0) map to i=0, 1, . . . , P_(CSIRS,SD)−1 and f=0, ports j=0,        1, . . . , P_(CSIRS,SD)−1 in all PRBs of the second segment        (index s=1) map to i=0, 1, . . . , P_(CSIRS,SD)−1 and f=1, and        so on. Mathematically, this is equivalent to i=j and f=s. Note        that the first segment (index s=0) includes PRBs (g=0 to g=y₀),        the second segment (index s=1) includes PRBs (g=y₀+1 to g=y₁),        and so on.    -   In one example Ex 1.3.3, the number of PRBs in a CSI reporting        band is partitioned into M segments with each segment s        comprising all PRB indices s+d×M, where s=0, 1, . . . , M−1 and        d=0, 1, . . . , X−1, and

${X = {\frac{N_{PRB}}{M}{or}\left\lceil \frac{N_{PRB}}{M} \right\rceil{or}\left\lfloor \frac{N_{PRB}}{M} \right\rfloor}},$

-   -    and N_(PRB) is a total number of PRBs in the CSI reporting        band. The ports j=0, 1, . . . , P_(CSIRS,SD)−1 in all PRBs of        the first segment (index s=0) map to i=0, 1, . . . ,        P_(CSIRS,SD)−1 and f=0, ports j=0, 1, . . . , P_(CSIRS,SD)−1 in        all PRBs of the second segment (index s=1) map to i=0, 1, . . .        , P_(CSIRS,SD)−1 and f=1, and so on. Note that when M=2, there        are two segments, one comprising even-numbered PRB indices 0, 2,        4, . . . , and another comprising odd-numbered PRB indices 1, 3,        5, . . . .

Likewise, for the case when the mapping is between CSI-RS ports and theSD-FD beam-forming vector indices (i, f), where i∈{0, 1, . . . ,P_(CSIRS)−1} and f∈{0, 1, . . . , O_(f)−1}, the mapping of CSI-RS port jto the index pair (i, f) is the same as in Alt 1.3 except that thenotation P_(CSIRS,SD) and P_(CSIRS,FD) are replaced with P_(CSIRS) andO_(f), respectively.

In one alternative Alt 1.4, it is assumed that all P_(CSIRS) CSI-RSports can be measured via (across) multiple CSI-RS resources (not withina single CSI-RS resource as in Alt 1.1/1.1a/1.2/1.2a), but the multipleCSI-RS resources are measured within each PRB of the configured BWP forCSI-RS measurement. The mapping of CSI-RS port j to the index pair (i,f) is the following order SD→FD, i.e., first in SD then in FD acrossmultiple CSI-RS resources. One example is given by the following.

-   -   Ports j=0, 1, . . . , P_(CSIRS,SD)−1 in the first CSI-RS        resource (index h=0) map to i=0, 1, . . . , P_(CSIRS,SD)−1 and        f=0, ports j=0, 1, . . . , P_(CSIRS,SD)−1 in the second CSI-RS        resource (index h=1) map to i=0, 1, . . . , P_(CSIRS,SD)−1 and        f=1, and so on. Mathematically, this is equivalent to i=j and        f=h.

Likewise, for the case when the mapping is between CSI-RS ports and theSD-FD beam-forming vector indices (i, f), where i∈{0, 1, . . . ,P_(CSIRS)−1} and f∈{0, 1, . . . , O_(f)−1}, the mapping of CSI-RS port jto the index pair (i, f) is the same as in Alt 1.4 except that thenotation P_(CSIRS,SD) and P_(CSIRS,FD) are replaced with P_(CSIRS) andO_(f), respectively.

In one alternative Alt 1.5, it is assumed that all P_(CSIRS) CSI-RSports can be measured via (across) multiple time slots/instances (notwithin a single time slot/instance as in Alt 1.1/1.1a/1.2/1.2a), but allP_(CSIRS) CSI-RS ports are measured within each PRB of the configuredBWP for CSI-RS measurement. The mapping of CSI-RS port j to the indexpair (i, f) is the following order SD→FD, i.e., first in SD then in FDacross multiple time slots. One example is given by the following.

-   -   Ports j=0, 1, . . . , P_(CSIRS,SD)−1 in the first time slot        (index k=0) map to i=0, 1, . . . , P_(CSIRS,SD)−1 and f=0, ports        j=0, 1, . . . , P_(CSIRS,SD)−1 in the second time slot (index        k=1) map to i=0, 1, . . . , P_(CSIRS,SD)−1 and f=1, and so on.        Mathematically, this is equivalent to i=j and f=k.

In a variation, multiple time slots/instances correspond to a multi-shottransmission of a single CSI-RS resource in multiple time slots (whichcan be consecutive or separated in time, but their locations areknown/configured to the UE). Alternatively, multiple timeslots/instances correspond to one-shot transmissions of multiple CSI-RSresources that are separated in time.

Likewise, for the case when the mapping is between CSI-RS ports and theSD-FD beam-forming vector indices (i, f), where i∈{0, 1, . . . ,P_(CSIRS)−1} and f∈{0, 1, . . . , O_(f)−1}, the mapping of CSI-RS port jto the index pair (i, f) is the same as in Alt 1.5 except that thenotation P_(CSIRS,SD) and P_(CSIRS,FD) are replaced with P_(CSIRS) andO_(f), respectively.

In one alternative Alt 1.6, it is assumed that all P_(CSIRS) CSI-RSports can be measured across multiple PRBs and multiple CSI-RS resources(not within each PRB and a single CSI-RS resource as in Alt1.1/1.1a/1.2/1.2a), but the multiple PRBs and multiple CSI-RS resourcesare within each FD unit of the configured BWP for CSI-RS measurement.For example, the P_(CSIRS,FD) FD ports can be divided into T parts, eachwith P_(CSIRS,FD) ⁽¹⁾ ports, i.e., P_(CSIRS,FD)=P_(CSIRS,FD) ⁽¹⁾×T,where T is the number of CSI-RS resources, and P_(CSIRS,FD) ⁽¹⁾ is thenumber of FD ports associated with each CSI-RS resource. For each CSIresource, the UE measures P_(CSIRS,SD)P_(CSIRS,FD) ⁽¹⁾ ports accordingto Alt 1.3, and measure ports for T such CSI-RS resources according toAlt 1.4.

Likewise, for the case when the mapping is between CSI-RS ports and theSD-FD beam-forming vector indices (i, f), where i∈{0, 1, . . . ,P_(CSIRS)−1} and f∈{0, 1, . . . , O_(f)−1}, the mapping of CSI-RS port jto the index pair (i, f) is the same as in Alt 1.6 except that thenotation P_(CSIRS,SD) and P_(CSIRS,FD) ⁽¹⁾ are replaced with P_(CSIRS)and O_(f) ⁽¹⁾, respectively, where

$O_{f}^{(1)} = {\frac{O_{f}}{T}.}$

In one alternative Alt 1.7, it is assumed that all P_(CSIRS) CSI-RSports can be measured across multiple PRBs and multiple time slots (notwithin each PRB and a single time slot as in Alt 1.1/1.1a/1.2/1.2a), butthe multiple PRBs are within each FD unit of the configured BWP forCSI-RS measurement. For example, the P_(CSIRS,FD) FD ports can bedivided into T parts, each with P_(CSIRS,FD) ⁽²⁾ ports, i.e.,P_(CSIRS,FD)=P_(CSIRS,FD) ⁽²⁾×U, where U is the number of time slots,and P_(CSIRS,FD) ⁽²⁾ is the number of FD ports associated with each timeslot. For each time slot, the UE measures P_(CSIRS,SD)P_(CSIRS,FD) ⁽²⁾ports according to Alt 1.3, and measure ports for U such time slotsaccording to Alt 1.5.

Likewise, for the case when the mapping is between CSI-RS ports and theSD-FD beam-forming vector indices (i, f), where i∈{0, 1, . . . ,P_(CSIRS)−1} and f∈{0, 1, . . . , O_(f)−1}, the mapping of CSI-RS port jto the index pair (i, f) is the same as in Alt 1.7 except that thenotation P_(CSIRS,SD) and P_(CSIRS,FD) ⁽¹⁾ are replaced with P_(CSIRS)and O_(f) ⁽¹⁾, respectively, where

$O_{f}^{(1)} = {\frac{O_{f}}{T}.}$

In one alternative Alt 1.8, it is assumed that all P_(CSIRS) CSI-RSports can be measured via (across) multiple CSI-RS resources andmultiple time slots (not within a single CSI-RS resource and a singletime slot/instance as in Alt 1.1/1.1a/1.2/1.2a), but the multiple CSI-RSresources are measured within each PRB of the configured BWP for CSI-RSmeasurement. For example, the P_(CSIRS,FD) FD ports can be divided intoTU parts, each with P_(CSIRS,FD) ⁽¹⁾P_(CSIRS,FD) ⁽²⁾ ports i.e.,P_(CSIRS,FD)=P_(CSIRS,FD) ⁽¹⁾P_(CSIRS,FD) ⁽²⁾×TU, where T is the numberof CSI-RS resources, U is the number of time slots, P_(CSIRS,FD)⁽¹⁾P_(CSIRS,FD) ⁽²⁾ is the number of FD ports associated with eachCSI-RS resource and each time slot, and P_(CSIRS,FD) ⁽¹⁾ is the numberof FD ports associated with each CSI-RS resource. For each CSI resourceand for each time slot, the UE measures P_(CSIRS,SD)P_(CSIRS,FD)⁽¹⁾P_(CSIRS,FD) ⁽²⁾ ports according to Alt 1.1/1/1a/1/2/1/2a, andmeasure ports for TU such combinations of CSI-RS resources and timeslots.

Likewise, for the case when the mapping is between CSI-RS ports and theSD-FD beam-forming vector indices (i, f), where i∈{0, 1, . . . ,P_(CSIRS)−1} and f∈{0, 1, . . . , O_(f)−1}, the mapping of CSI-RS port jto the index pair (i, f) is the same as in Alt 1.8 except that thenotation P_(CSIRS,SD), P_(CSIRS,FD) ⁽¹⁾ and P_(CSIRS,FD) ⁽²⁾ arereplaced with P_(CSIRS), O_(f) ⁽¹⁾, and O_(f) ⁽²⁾, respectively, where

$O_{f}^{(1)} = {{\frac{O_{f}}{T}{and}O_{f}^{(2)}} = {\frac{O_{f}}{U}.}}$

In one alternative Alt 1.9, it is assumed that all P_(CSIRS) CSI-RSports can be measured via (across) multiple PRBs, multiple CSI-RSresources, and multiple time slots (not within each PRB, a single CSI-RSresource, and a single time slot/instance as in Alt 1.1/1.1a/1.2/1.2a),but the multiple CSI-RS resources are measured within each PRB of theconfigured BWP for CSI-RS measurement.

In some of the above alternatives, when the number of CSI-RS resourcesis more than one, at least one of the following examples is used for CRIreporting. In one example, the number of CSI-RS resources equals M,hence all CSI-RS resources are used to construct {tilde over (W)}₂, andCRI is not reported. In another example, the number of CSI-RS resourcesexceeds (or is greater than) M, hence M CSI-RS resources are selected bythe UE, and the selected CSI-RS resources are reported as part of theCSI report, for example, using a single CRI indicating the selectedCSI-RS resources or using multiple CRIs (e.g., 1 CRI for 1 selectedCSI-RS resource).

In some of the above alternatives, when the number of time slots is morethan one, at least one of the following examples is used for anindicator (SI) indicating the selected time slots. In one example, thenumber of time slots equals M, hence CSI-RS ports measured in all timeslots are used to construct {tilde over (W)}₂ and SI is not reported. Inanother example, the number of time slots exceeds (or is greater than)M, hence M time slots are selected by the UE, and the selected timeslots are reported as part of the CSI report, for example, using asingle indicator (e.g., slot indicator SI) indicating the selected timeslots or using multiple indicators (e.g., 1 SI for 1 selected timeslot).

In one example, only one of the above alternatives for port numbering orthe mapping between CSI-RS ports and the SD-FD beam-forming vectorindices is used (hence fixed), for example, Alt 1.1 is used. In anotherexample, more than one of the above alternatives for port numbering orthe mapping between CSI-RS ports and the SD-FD beam-forming vectorindices can be used, and one them is configured (for example, via higherlayer RRC signaling).

In some of the above alternatives, when the number of CSI-RS resourcesis more than one, at least one of the following examples is usedregarding the band-widths BWs of the CSI-RS resources. Let B_(i) be theBW of the i-th CSI-RS resource. In one example, the BWs of all CSI-RSresources are the same, i.e., B_(i)=B for all i, and they are within theCSI reporting band, i.e., B is a subset of the CSI reporting band. Inanother example, two of the multiple CSI-RS resources (i and j) can havedifferent BWs, i.e., B_(i)≠B_(j) for some i and j, but they are withinthe CSI reporting band, i.e., B_(i) and B_(j) are subsets of the CSIreporting band. In another example, when the number of CSI-RS resourcesequals two, one resource occupies even numbered PRBs of the CSIreporting band and another occupies odd numbered PRBs of the CSIreporting band, and each of the two CSI-RS resources has

$\frac{P_{CSIRS}}{2}$CSI-RS ports. In another example, when the number of CSI-RS resourcesequals two, one resource occupies one half of the total PRBs of the CSIreporting band and another occupies odd another half of the total PRBsof the CSI reporting band, and each of the two CSI-RS resources has

$\frac{P_{CSIRS}}{2}$CSI-RS ports.

In another example, when the number of CSI-RS resources equals O_(f)≥1,each resource occupies (transmitted in) a segment (portion) of the CSIreporting band comprising N_(PRB) PRBs. In one example, the detailsabout the segments is as explained in Example 1.3.3. In one example,each of O_(f) CSI-RS resources has the same number of CSI-RS ports. Inone example, the number of CSI-RS ports can be different across CSI-RSresources.

In embodiment 2, a UE is configured with one or multiple CSI-RSresources satisfying some constraints or restrictions when configuredfor the purpose CSI reporting as explained in embodiment 1. At least oneof the following alternatives is used as constraint or restriction.

In one alternative Alt 2.1, the restriction is on the number of CSI-RSports P_(CSIRS). Note that the number of CSI-RS ports P_(CSIRS)∈S₁={4,8,12,16,24,32} in Rel. 15/16 NR. At least one of the followingexamples is used.

-   -   In one example Ex 2.1.1, P_(CSIRS) ∈S₁={4,8,12,16,24,32}.    -   In one example Ex 2.1.2, P_(CSIRS) ∈S₂ where S₂ is a union of        {4,8,12,16,24,32} and a set of additional values T.        -   In one example, T includes values less than 32. For example,            T={20,28}, hence S₂={4,8,12,16,20,24,28,32}.        -   In one example, T includes values greater than 32. For            example, T={36,40}, hence S₂={4,8,12,16,24,32,36,40}.        -   In one example, T includes values less than 32 or greater            than 32. For example, T={20,28,36,40}, hence            S₂={4,8,12,16,20,24,28,32,36,40}.    -   In one example Ex 2.1.3, P_(CSIRS) ∈S₃ where S₃ is a subset of        {4,8,12,16,24,32}.        -   In one example, S₃={8,12,16,24,32}.        -   In one example, S₃ is determined such that P_(CSIRS)=a×2LM,            where a is a positive integer. For example, a=1 or a∈{1,2}.            Or, the value a may depend on the value of (L, M) or 2LM.        -   In one example, S₃ is determined such that

${P_{CSIRS} = {\frac{1}{a} \times 2{LM}}},$where a is a positive integer. For example, a=1 or a∈{1,2}. Or, thevalue a may depend on the value of (L, M) or 2LM.

In one alternative Alt 2.2, the restriction is on the density d (definedas a number of REs per PRB per CSI-RS port) of CSI-RS ports P_(CSIRS).Note that the density d∈{0,5,1,3} in Rel. 15/16 NR. At least one of thefollowing examples is used.

-   -   In one example Ex 2.2.0, the density is restricted to d=0.25        only.    -   In one example Ex 2.2.1, the density is restricted to d=0.5        only.    -   In one example Ex 2.2.2, the density is restricted to d=1 only.    -   In one example Ex 2.2.3, the density is restricted to d=1 or        d=0.5 based on a fixed condition. At least one of the following        examples is used for the fixed condition.        -   In one example, d=1 when P_(CSIRS)≤p and d=0.5 when            P_(CSIRS)>p. For example, p=8 or 16.        -   In one example, d=1 when 2LM≤q and d=0.5 when 2LM>q. For            example, q=8 or 16.        -   In one example, d=1 when L=2 and d=0.5 when L=4.    -   In one example Ex 2.2.4, the density is restricted to x/O_(f)        where x=1 or 0.5, and O_(f) is according to some embodiments of        this disclosure.    -   In one example Ex 2.2.5, the density is restricted to d=1 or        d=x/Of based on a fixed condition, where x=1 or 0.5, and O_(f)        is according to some embodiments of this disclosure. At least        one of the following examples is used for the fixed condition.        -   In one example, d=1 when P_(CSIRS)≤p and d=x/O_(f) when            P_(CSIRS)>p. For example, p=8 or 16.        -   In one example, d=1 when 2LM≤q and d=x/O_(f) when 2LM>q. For            example, q=8 or 16.        -   In one example, d=1 when L=2 and d=x/O_(f) when L=4.

In one example, the density d is configured from a set of supportedvalues, e.g., {x, x/O_(f)}. In one example, the set of supported valuesis reported by the UE as part of the UE capability reporting. In oneexample, d=x is mandatory for all UEs supporting the proposed codebookin embodiment 1. The support of any additional value (e.g.,

$\left. {d = \frac{x}{O_{f}}} \right)$or multiple values is subject to a separate UE capability signaling.

In one alternative Alt 2.3, the restriction is on the set of supportedcombination for parameters such as P_(CSIRS), L, p_(v), and β. At leastone of the following examples is used.

-   -   In one example Ex 2.3.1, the restriction is on the set of        supported combination for parameters (P_(CSIRS), L, p_(v)) for        rank 1-2 only (v∈{1,2}). An example of the value for (L, p_(v))        is shown in Table 3. The set of supported combination for        parameters (P_(CSIRS), L, p_(v)) for rank 1-2 includes        (P_(CSIRS), L, p_(v)) such that 2LM_(v)≤P_(CSIRS), (L, p_(v)) is        according to Table 3 and P_(CSIRS)∈S₁={4,8,12,16,24,32}.

TABLE 3 p_(v) paramCombination-r17 L v ∈ {1, 2} 1 2 ⅛ 2 2 ¼ 3 4 ¼ 4 4 ½

-   -   In one example Ex 2.3.2, the restriction is on the set of        supported combination for parameters (P_(CSIRS), L, P_(v), β)        for rank 1-2 only (v∈{1,2}). An example of the value for (L,        p_(v), β) is shown in Table 4. The set of supported combination        for parameters (P_(CSIRS), L, p_(v), β) for rank 1-2 includes        (P_(CSIRS), L, p_(v)) such that 2LM_(v)≤P_(CSIRS), (L, P_(v)) is        according to Table 4 and P_(CSIRS) ∈S₁={4,8,12,16,24,32}, and        the UE reports at most K₀=┌β2LM₁┐ nonzero coefficients (of        {tilde over (W)}₂) for layer l=1, . . . , v.

TABLE 4 p_(v) paramCombination-r17 L v ∈ {1, 2} β 1 2 ¼ ¼ 2 2 ¼ ½ 3 4 ¼¼ 4 4 ¼ ½ 5 4 ¼ ¾ 6 4 ½ ½

-   -   In Ex 2.3.3, the restriction is on the set of supported        combination for parameters (P_(CSIRS), L, p_(v), β) for rank 1-4        (v∈{1,2,3,4}). An example of the value for (L, p_(v), β) is        shown in Table 5. The set of supported combination for        parameters (P_(CSIRS), L, p_(v), β) for rank 1-4 includes        (P_(CSIRS), L, p_(v)) such that 2LM_(v)≤P_(CSIRS), (L, p_(v)) is        according to Table 5 and P_(CSIRS) ∈S₁={4,8,12,16,24,32}, and        the UE reports at most K₀=┌β2LM₁┐ nonzero coefficients (of        {tilde over (W)}₂) for layer l=1, . . . , v.

TABLE 5 p_(v) paramCombination-r17 L v ∈ {1, 2} v ∈ {3, 4} β 1 2 ¼ ⅛ ¼ 22 ¼ ⅛ ½ 3 4 ¼ ⅛ ¼ 4 4 ¼ ⅛ ½ 5 4 ¼ ¼ ¾ 6 4 ½ ¼ ½

In one alternative Alt 2.4, the restriction is on the time domainconfiguration. At least one of the following examples is used.

-   -   In one example Ex 2.4.1, when there is only one CSI-RS resource,        the CSI-RS resource is aperiodic (triggered via DCI).    -   In one example Ex 2.4.2, when there is only one CSI-RS resource,        the CSI-RS resource is semi-persistent (SP)        (activated/deactivated via MAC CE activation/deactivation        command). In one example, the SP CSI-RS transmission corresponds        to a multi-shot transmission with a number of transmission        instances (time slots) equal to M or a multiple of M.    -   In one example Ex 2.4.3, when there is only one CSI-RS resource,        the CSI-RS resource is aperiodic (triggered via DCI) or        semi-persistent (activated/deactivated via MAC CE        activation/deactivation command) based on a fixed condition. At        least one of the following examples is used for the fixed        condition.        -   In one example, the CSI-RS resource is aperiodic when            P_(CSIRS)≤p and the CSI-RS resource is semi-persistent when            P_(CSIRS)>p. For example, p=8 or 16.        -   In one example, the CSI-RS resource is aperiodic when 2LM≤q            and the CSI-RS resource is semi-persistent when 2LM>q. For            example, q=8 or 16.        -   In one example, the CSI-RS resource is aperiodic when L=2            and the CSI-RS resource is semi-persistent when L=4.

In one example Ex 2.4.4, when there are multiple CSI-RS resources, theCSI-RS resources are all aperiodic (triggered via DCI), but they aretransmitted in different time slots (i.e., 1 CSI-RS resource istransmitted in each time slot).

In one example Ex 2.4.5, when there are multiple CSI-RS resources, theCSI-RS resources are all aperiodic (triggered via DCI), and up to ZCSI-RS resources can be transmitted in the same time slot. If there aremore than Z CSI-RS resources, then some of them are transmitted indifferent time slots (i.e., up to Z CSI-RS resources can be transmittedin each time slot). In one example, Z=2.

Any of the above variation embodiments can be utilized independently orin combination with at least one other variation embodiment.

FIG. 15 illustrates a flow chart of a method 1500 for operating a userequipment (UE), as may be performed by a UE such as UE 116, according toembodiments of the present disclosure. The embodiment of the method 1500illustrated in FIG. 15 is for illustration only. FIG. 15 does not limitthe scope of this disclosure to any particular implementation.

As illustrated in FIG. 15 , the method 1500 begins at step 1502. In step1502, the UE (e.g., 111-116 as illustrated in FIG. 1 ) receivesconfiguration information for at least one channel state informationreference signal (CSI-RS) resource that comprises P_(CSIRS) CSI-RSports.

In step 1504, the UE receives configuration information for channelstate information (CSI) feedback that is based on Q precodingdimensions, wherein: there is a mapping between the P_(CSIRS) CSI-RSports and the Q precoding dimensions, and P_(CSIRS)≠Q.

In step 1506, the UE measures the P_(CSIRS) CSI-RS ports.

In step 1508, the UE determines a measurement for the Q precodingdimensions based on the mapping and the measurement for the P_(CSIRS)CSI-RS ports.

In step 1510, the UE determines a CSI feedback based on the measurementfor the Q precoding dimensions.

In step 1512, the UE transmits, over an uplink (UL) channel, thedetermined CSI feedback.

In one embodiment, a precoding dimension is associated with a CSI-RSport via a beamforming vector that precodes the CSI-RS resourcetransmitted from the CSI-RS port.

In one embodiment, P_(CSIRS)×O_(f)=Q, wherein O_(f)=a number ofprecoding dimensions per CSI-RS port.

In one embodiment, the mapping corresponds to a frequency divisionmultiplexing (FDM) of the O_(f) precoding dimensions via each CSI-RSport.

In one embodiment, O_(f)=2, and the FDM is such that a first precodingdimension is associated with even numbered physical resource blocks(PRBs) and a second precoding dimension is associated with odd numberedPRBs.

In one embodiment, the mapping is based on multiple CSI-RS resourcessuch that: a number of CSI-RS resources

${O_{f} = \frac{Q}{P_{CSIRS}}};$Q=a total number of precoding dimensions across O_(f) CSI-RS resources;P_(CSIRS)=a number of CSI-RS ports per CSI-RS resource.

In one embodiment, the mapping is based on a value of CSI-RS density,where the value of the CSI-RS density is configured such that the Qprecoding dimensions are conveyed based on the P_(CSIRS) CSI-RS ports.

FIG. 16 illustrates a flow chart of another method 1600, as may beperformed by a base station (BS) such as BS 102, according toembodiments of the present disclosure. The embodiment of the method 1600illustrated in FIG. 16 is for illustration only. FIG. 16 does not limitthe scope of this disclosure to any particular implementation.

As illustrated in FIG. 16 , the method 1600 begins at step 1602. In step1602, the BS (e.g., 101-103 as illustrated in FIG. 1 ), generatesconfiguration information for at least one channel state informationreference signal (CSI-RS) resource that comprises P_(CSIRS) CSI-RSports.

In step 1604, the BS generates configuration information for channelstate information (CSI) feedback that is based on Q precodingdimensions, wherein: there is a mapping between the P_(CSIRS) CSI-RSports and the Q precoding dimensions, and P_(CSIRS)≠Q.

In step 1606, the BS transmits the configuration information for the atleast one CSI-RS resource.

In step 1608, the BS transmits the configuration information for the CSIfeedback.

In step 1610, the BS transmits the at least one CSI-RS resource from theP_(CSIRS) CSI-RS ports.

In step 1612, the BS receives, over an uplink (UL) channel, the CSIfeedback; wherein: the CSI feedback is based on the Q precodingdimensions, and the Q precoding dimensions are based on the mapping andthe P_(CSIRS) CSI-RS ports.

In one embodiment, wherein a precoding dimension is associated with aCSI-RS port via a beamforming vector that precodes the CSI-RS resourcetransmitted from the CSI-RS port.

In one embodiment, P_(CSIRS)×O_(f)=Q, wherein O_(f)=a number ofprecoding dimensions per CSI-RS port.

In one embodiment, the mapping corresponds to a frequency divisionmultiplexing (FDM) of the O_(f) precoding dimensions via each CSI-RSport.

In one embodiment, O_(f)=2, and the FDM is such that a first precodingdimension is associated with even numbered PRBs and a second precodingdimension is associated with odd numbered PRB s.

In one embodiment, the mapping is based on multiple CSI-RS resourcessuch that: a number of CSI-RS resources

${O_{f} = \frac{Q}{P_{CSIRS}}};$Q=a total number of precoding dimensions across O_(f) CSI-RS resources;P_(CSIRS)=a number of CSI-RS ports per CSI-RS resource.

In one embodiment, the mapping is based on a value of CSI-RS density,where the value of the CSI-RS density is configured such that the Qprecoding dimensions are conveyed based on the P_(CSIRS) CSI-RS ports.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims. None of the description in this application should be read asimplying that any particular element, step, or function is an essentialelement that must be included in the claims scope. The scope of patentedsubject matter is defined by the claims.

What is claimed is:
 1. A user equipment (UE) comprising: a transceiverconfigured to: receive configuration information for at least onechannel state information reference signal (CSI-RS) resource thatcomprises a number (P_(CSIRS)) of CSI-RS ports (P_(CSIRS) CSI-RS ports);and receive configuration information for channel state information(CSI) feedback that is based on a number (Q) of precoding dimensions (Qprecoding dimensions), wherein: there is a mapping between the P_(CSIRS)CSI-RS ports and the Q precoding dimensions, and P_(CSIRS)≠Q; and aprocessor operably coupled to the transceiver, the processor configuredto: measure the P_(CSIRS) CSI-RS ports; determine a measurement for theQ precoding dimensions based on the mapping and the measurement for theP_(CSIRS) CSI-RS ports; and determine a CSI feedback based on themeasurement for the Q precoding dimensions; wherein the transceiver isfurther configured to transmit, over an uplink (UL) channel, thedetermined CSI feedback.
 2. The UE of claim 1, wherein each precodingdimension is associated with a CSI-RS port via a beamforming vector thatprecodes the CSI-RS resource transmitted from the CSI-RS port.
 3. The UEof claim 1, wherein P_(CSIRS)×O_(f)=Q, wherein O_(f)=a number ofprecoding dimensions per CSI-RS port.
 4. The UE of claim 3, wherein themapping corresponds to a frequency division multiplexing (FDM) of theO_(f) precoding dimensions via each CSI-RS port.
 5. The UE of claim 4,wherein O_(f)=2, and the FDM is such that a first precoding dimension isassociated with even numbered physical resource blocks (PRBs) and asecond precoding dimension is associated with odd numbered PRBs.
 6. TheUE of claim 1, wherein the mapping is based on multiple CSI-RS resourcessuch that: a number of CSI-RS resources ${O_{f} = \frac{Q}{P_{CSIRS}}};$Q=a total number of precoding dimensions across O_(f) CSI-RS resources;and P_(CSIRS)=a number of CSI-RS ports per CSI-RS resource.
 7. The UE ofclaim 1, wherein the mapping is based on a value of CSI-RS density,where the value of the CSI-RS density is configured such that the Qprecoding dimensions are conveyed based on the P_(CSIRS) CSI-RS ports.8. A base station (BS) comprising: a processor configured to: generateconfiguration information for at least one channel state informationreference signal (CSI-RS) resource that comprises a number (P_(CSIRS))of ports CSI-RS (P_(CSIRS) CSI-RS ports); and generate configurationinformation for channel state information (CSI) feedback that is basedon a number (Q) of precoding dimensions (Q precoding dimensions),wherein: there is a mapping between the P_(CSIRS) CSI-RS ports and the Qprecoding dimensions, and P_(CSIRS)≠Q; and a transceiver operablycoupled to the processor, the transceiver configured to: transmit theconfiguration information for the at least one CSI-RS resource; transmitthe configuration information for the CSI feedback; transmit the atleast one CSI-RS resource from the P_(CSIRS) CSI-RS ports; and receive,over an uplink (UL) channel, the CSI feedback; wherein: the CSI feedbackis based on the Q precoding dimensions, and the Q precoding dimensionsare based on the mapping and the P_(CSIRS) CSI-RS ports.
 9. The BS ofclaim 8, wherein each precoding dimension is associated with a CSI-RSport via a beamforming vector that precodes the CSI-RS resourcetransmitted from the CSI-RS port.
 10. The BS of claim 8, whereinP_(CSIRS)×O_(f)=Q, wherein O_(f)=a number of precoding dimensions perCSI-RS port.
 11. The BS of claim 10, wherein the mapping corresponds toa frequency division multiplexing (FDM) of the O_(f) precodingdimensions via each CSI-RS port.
 12. The BS of claim 11, whereinO_(f)=2, and the FDM is such that a first precoding dimension isassociated with even numbered PRBs and a second precoding dimension isassociated with odd numbered PRBs.
 13. The BS of claim 8, wherein themapping is based on multiple CSI-RS resources such that: a number ofCSI-RS resources ${O_{f} = \frac{Q}{P_{CSIRS}}};$ Q=a total number ofprecoding dimensions across O_(f) CSI-RS resources; and P_(CSIRS)=anumber of CSI-RS ports per CSI-RS resource.
 14. The BS of claim 8,wherein the mapping is based on a value of CSI-RS density, where thevalue of the CSI-RS density is configured such that the Q precodingdimensions are conveyed based on the P_(CSIRS) CSI-RS ports.
 15. Amethod for operating a user equipment (UE), the method comprising:receiving configuration information for at least one channel stateinformation reference signal (CSI-RS) resource that comprises a number(P_(CSIRS)) of CSI-RS ports (P_(CSIRS) CSI-RS ports); and receivingconfiguration information for channel state information (CSI) feedbackthat is based on a number (Q) of precoding dimensions (Q precodingdimensions), wherein: there is a mapping between the P_(CSIRS) CSI-RSports and the Q precoding dimensions, and P_(CSIRS)≠Q; measuring theP_(CSIRS) CSI-RS ports; determining a measurement for the Q precodingdimensions based on the mapping and the measurement for the P_(CSIRS)CSI-RS ports; determining a CSI feedback based on the measurement forthe Q precoding dimensions; and transmitting, over an uplink (UL)channel, the determined CSI feedback.
 16. The method of claim 15,wherein each precoding dimension is associated with a CSI-RS port via abeamforming vector that precodes the CSI-RS resource transmitted fromthe CSI-RS port.
 17. The method of claim 15, wherein P_(CSIRS)×O_(f)=Q,wherein O_(f)=a number of precoding dimensions per CSI-RS port.
 18. Themethod of claim 17, wherein the mapping corresponds to a frequencydivision multiplexing (FDM) of the O_(f) precoding dimensions via eachCSI-RS port.
 19. The method of claim 18, wherein O_(f)=2, and the FDM issuch that a first precoding dimension is associated with even numberedPRBs and a second precoding dimension is associated with odd numberedPRBs.
 20. The method of claim 15, wherein the mapping is based onmultiple CSI-RS resources such that: a number of CSI-RS resources${O_{f} = \frac{Q}{P_{CSIRS}}};$ Q=a total number of precodingdimensions across O_(f) CSI-RS resources; and P_(CSIRS)=a number ofCSI-RS ports per CSI-RS resource.